Error handling

2025-06-21 20:49:08 +02:00
Commit 0a994fa648
--- a/v2_adminpanel/ERROR_HANDLING_GUIDE.md
+++ b/v2_adminpanel/ERROR_HANDLING_GUIDE.md
@@ -0,0 +1,456 @@
+# Error Handling Guide
+
+## Overview
+
+This guide describes the error handling system implemented in the v2_adminpanel application. The system provides:
+
+- Centralized error handling with custom exception hierarchy
+- Input validation framework
+- Structured logging
+- Monitoring and alerting
+- Consistent error responses
+
+## Architecture
+
+### 1. Custom Exception Hierarchy
+
+```
+BaseApplicationException
+├── ValidationException
+│   ├── InputValidationError
+│   ├── BusinessRuleViolation
+│   └── DataIntegrityError
+├── AuthenticationException
+│   ├── InvalidCredentialsError
+│   ├── SessionExpiredError
+│   └── InsufficientPermissionsError
+├── DatabaseException
+│   ├── ConnectionError
+│   ├── QueryError
+│   └── TransactionError
+├── ExternalServiceException
+│   ├── APIError
+│   └── TimeoutError
+└── ResourceException
+    ├── ResourceNotFoundError
+    ├── ResourceConflictError
+    └── ResourceLimitExceeded
+```
+
+### 2. Core Components
+
+- **core/exceptions.py**: Custom exception classes
+- **core/error_handlers.py**: Global error handlers and decorators
+- **core/validators.py**: Input validation framework
+- **core/logging_config.py**: Structured logging setup
+- **core/monitoring.py**: Error metrics and alerting
+- **middleware/error_middleware.py**: Request-level error handling
+
+## Usage Examples
+
+### 1. Raising Custom Exceptions
+
+```python
+from core.exceptions import (
+    InputValidationError, 
+    ResourceNotFoundError,
+    BusinessRuleViolation
+)
+
+# Validation error
+if not email_is_valid:
+    raise InputValidationError(
+        field='email',
+        message='Invalid email format',
+        value=email_value,
+        expected_type='email'
+    )
+
+# Resource not found
+user = db.get_user(user_id)
+if not user:
+    raise ResourceNotFoundError(
+        resource_type='User',
+        resource_id=user_id
+    )
+
+# Business rule violation
+if active_licenses >= license_limit:
+    raise BusinessRuleViolation(
+        rule='license_limit',
+        message='License limit exceeded',
+        context={
+            'current': active_licenses,
+            'limit': license_limit
+        }
+    )
+```
+
+### 2. Using Error Decorators
+
+```python
+from core.error_handlers import handle_errors, validate_request
+from core.validators import validate
+
+@handle_errors(
+    catch=(psycopg2.Error,),
+    message='Database operation failed',
+    user_message='Datenbankfehler aufgetreten',
+    redirect_to='admin.dashboard'
+)
+def update_customer(customer_id):
+    # Database operations
+    pass
+
+@validate_request(
+    required_fields={
+        'email': str,
+        'age': int,
+        'active': bool
+    }
+)
+def create_user():
+    # Request data is validated
+    pass
+
+@validate({
+    'email': {
+        'type': 'email',
+        'required': True
+    },
+    'password': {
+        'type': 'password',
+        'required': True
+    },
+    'age': {
+        'type': 'integer',
+        'required': True,
+        'min_value': 18,
+        'max_value': 120
+    }
+})
+def register_user():
+    # Access validated data
+    data = request.validated_data
+    # Use data safely
+```
+
+### 3. Input Validation
+
+```python
+from core.validators import Validators
+
+# Email validation
+email = Validators.email(user_input, field_name='email')
+
+# Phone validation
+phone = Validators.phone(user_input, field_name='phone')
+
+# License key validation
+license_key = Validators.license_key(user_input)
+
+# Integer with constraints
+age = Validators.integer(
+    user_input,
+    field_name='age',
+    min_value=0,
+    max_value=150
+)
+
+# String with constraints
+username = Validators.string(
+    user_input,
+    field_name='username',
+    min_length=3,
+    max_length=50,
+    safe_only=True
+)
+
+# Password validation
+password = Validators.password(user_input)
+
+# Custom enum validation
+status = Validators.enum(
+    user_input,
+    field_name='status',
+    allowed_values=['active', 'inactive', 'pending']
+)
+```
+
+### 4. Error Context Manager
+
+```python
+from core.error_handlers import ErrorContext
+
+with ErrorContext(
+    operation='create_license',
+    resource_type='License',
+    resource_id=license_key
+):
+    # Operations that might fail
+    db.insert_license(license_data)
+    # Errors are automatically logged with context
+```
+
+### 5. Logging
+
+```python
+from core.logging_config import get_logger, log_error, log_security_event
+
+logger = get_logger(__name__)
+
+# Standard logging
+logger.info('User created', extra={
+    'user_id': user.id,
+    'email': user.email
+})
+
+# Error logging
+try:
+    risky_operation()
+except Exception as e:
+    log_error(
+        logger,
+        'Risky operation failed',
+        error=e,
+        user_id=user.id,
+        operation='risky_operation'
+    )
+
+# Security event logging
+log_security_event(
+    'INVALID_LOGIN_ATTEMPT',
+    'Multiple failed login attempts',
+    username=username,
+    ip_address=request.remote_addr,
+    attempt_count=5
+)
+```
+
+## Error Response Format
+
+### JSON Responses (API)
+
+```json
+{
+    "error": {
+        "code": "VALIDATION_ERROR",
+        "message": "Invalid input provided",
+        "timestamp": "2024-01-15T10:30:00Z",
+        "request_id": "550e8400-e29b-41d4-a716-446655440000",
+        "details": {
+            "field": "email",
+            "value": "invalid-email",
+            "expected_type": "email"
+        }
+    }
+}
+```
+
+### HTML Responses
+
+- User-friendly error messages
+- Error code and request ID for support
+- Helpful suggestions for resolution
+- Navigation options (back, dashboard, retry)
+
+## Monitoring and Alerts
+
+### Metrics Exposed
+
+- `app_errors_total`: Total error count by code, status, endpoint
+- `app_error_rate`: Errors per minute by error code
+- `app_validation_errors_total`: Validation errors by field
+- `app_auth_failures_total`: Authentication failures
+- `app_database_errors_total`: Database errors
+- `app_request_duration_seconds`: Request duration histogram
+
+### Alert Thresholds
+
+- Error rate > 10/min: Critical alert
+- Auth failure rate > 5/min: Security alert
+- DB error rate > 3/min: Infrastructure alert
+- Response time 95th percentile > 2s: Performance alert
+
+### Accessing Metrics
+
+- Prometheus metrics: `/metrics`
+- Active alerts: `/api/alerts`
+
+## Best Practices
+
+### 1. Always Use Specific Exceptions
+
+```python
+# Bad
+raise Exception("User not found")
+
+# Good
+raise ResourceNotFoundError('User', user_id)
+```
+
+### 2. Provide Context
+
+```python
+# Bad
+raise ValidationException("Invalid data")
+
+# Good
+raise InputValidationError(
+    field='email',
+    message='Email domain not allowed',
+    value=email,
+    expected_type='corporate_email'
+)
+```
+
+### 3. Handle Database Errors
+
+```python
+# Bad
+result = db.execute(query)
+
+# Good
+try:
+    result = db.execute(query)
+except psycopg2.IntegrityError as e:
+    if e.pgcode == '23505':
+        raise DataIntegrityError(
+            entity='User',
+            constraint='unique_email',
+            message='Email already exists'
+        )
+    raise
+```
+
+### 4. Validate Early
+
+```python
+# Bad
+def process_order(data):
+    # Process without validation
+    total = data['quantity'] * data['price']
+
+# Good
+@validate({
+    'quantity': {'type': 'integer', 'min_value': 1},
+    'price': {'type': 'float', 'min_value': 0}
+})
+def process_order():
+    data = request.validated_data
+    total = data['quantity'] * data['price']
+```
+
+### 5. Log Security Events
+
+```python
+# Failed login attempts
+log_security_event(
+    'LOGIN_FAILURE',
+    f'Failed login for user {username}',
+    username=username,
+    ip_address=request.remote_addr
+)
+
+# Suspicious activity
+log_security_event(
+    'SUSPICIOUS_ACTIVITY',
+    'Rapid API requests detected',
+    ip_address=request.remote_addr,
+    request_count=count,
+    time_window=60
+)
+```
+
+## Migration Guide
+
+### Converting Existing Error Handling
+
+1. **Replace generic exceptions**:
+```python
+# Old
+except Exception as e:
+    flash(f"Error: {str(e)}", "error")
+    return redirect(url_for('admin.dashboard'))
+
+# New
+except DatabaseException as e:
+    # Already handled by global handler
+    raise
+```
+
+2. **Update validation**:
+```python
+# Old
+email = request.form.get('email')
+if not email or '@' not in email:
+    flash("Invalid email", "error")
+    return redirect(request.url)
+
+# New
+from core.validators import Validators
+try:
+    email = Validators.email(request.form.get('email'))
+except InputValidationError as e:
+    # Handled automatically
+    raise
+```
+
+3. **Use decorators**:
+```python
+# Old
+@app.route('/api/user', methods=['POST'])
+def create_user():
+    try:
+        # validation code
+        # database operations
+    except Exception as e:
+        return jsonify({'error': str(e)}), 500
+
+# New
+@app.route('/api/user', methods=['POST'])
+@validate({
+    'email': {'type': 'email', 'required': True},
+    'name': {'type': 'string', 'required': True, 'min_length': 2}
+})
+def create_user():
+    data = request.validated_data
+    # Use validated data directly
+```
+
+## Testing
+
+Run the test suite:
+
+```bash
+pytest v2_adminpanel/tests/test_error_handling.py -v
+```
+
+Test coverage includes:
+- Exception creation and properties
+- Error handler responses (JSON/HTML)
+- Validation functions
+- Decorators
+- Monitoring and metrics
+- Alert generation
+
+## Troubleshooting
+
+### Common Issues
+
+1. **Import errors**: Ensure you import from `core` package
+2. **Validation not working**: Check decorator order (validate must be closest to function)
+3. **Logs not appearing**: Verify LOG_LEVEL environment variable
+4. **Metrics missing**: Ensure prometheus_client is installed
+
+### Debug Mode
+
+In development, set:
+```python
+app.config['DEBUG'] = True
+```
+
+This will:
+- Include detailed error information
+- Show stack traces
+- Log to console with readable format
--- a/v2_adminpanel/app.py
+++ b/v2_adminpanel/app.py
@@ -16,6 +16,12 @@ from prometheus_flask_exporter import PrometheusMetrics
 import config
 from utils.backup import create_backup

+# Import error handling system
+from core.error_handlers import init_error_handlers
+from core.logging_config import setup_logging
+from core.monitoring import init_monitoring
+from middleware.error_middleware import ErrorHandlingMiddleware
+
 app = Flask(__name__)

 # Initialize Prometheus metrics
@@ -41,6 +47,12 @@ app.wsgi_app = ProxyFix(

 # Configuration is now loaded from config module

+# Initialize error handling system
+setup_logging(app)
+init_error_handlers(app)
+init_monitoring(app)
+ErrorHandlingMiddleware(app)
+
 # Scheduler für automatische Backups
 scheduler = BackgroundScheduler()
 scheduler.start()
@@ -129,24 +141,7 @@ scheduler.add_job(
 )


-# Error handlers
-@app.errorhandler(404)
-def not_found(e):
-    try:
-        return render_template('404.html'), 404
-    except:
-        return "404 - Page not found", 404
-
-
-@app.errorhandler(500)
-def server_error(e):
-    import traceback
-    error_msg = f"Server error: {str(e)}\n{traceback.format_exc()}"
-    logging.error(error_msg)
-    try:
-        return render_template('500.html'), 500
-    except:
-        return f"500 - Internal Server Error\n\n{error_msg}", 500
+# Error handlers are now managed by the error handling system in core/error_handlers.py


 # Context processors
--- a/v2_adminpanel/core/init.py
+++ b/v2_adminpanel/core/init.py
--- a/v2_adminpanel/core/error_handlers.py
+++ b/v2_adminpanel/core/error_handlers.py
@@ -0,0 +1,273 @@
+import logging
+import traceback
+from functools import wraps
+from typing import Optional, Dict, Any, Callable, Union
+from flask import (
+    Flask, request, jsonify, render_template, flash, redirect, 
+    url_for, current_app, g
+)
+from werkzeug.exceptions import HTTPException
+import psycopg2
+
+from .exceptions import (
+    BaseApplicationException, DatabaseException, ValidationException,
+    AuthenticationException, ResourceException, QueryError,
+    ConnectionError, TransactionError
+)
+
+
+logger = logging.getLogger(__name__)
+
+
+def init_error_handlers(app: Flask) -> None:
+    @app.before_request
+    def before_request():
+        g.request_id = request.headers.get('X-Request-ID', 
+                                         BaseApplicationException('', '', 0).request_id)
+    
+    @app.errorhandler(BaseApplicationException)
+    def handle_application_error(error: BaseApplicationException):
+        return _handle_error(error)
+    
+    @app.errorhandler(HTTPException)
+    def handle_http_error(error: HTTPException):
+        return _handle_error(error)
+    
+    @app.errorhandler(psycopg2.Error)
+    def handle_database_error(error: psycopg2.Error):
+        db_exception = _convert_psycopg2_error(error)
+        return _handle_error(db_exception)
+    
+    @app.errorhandler(Exception)
+    def handle_unexpected_error(error: Exception):
+        logger.error(
+            f"Unexpected error: {str(error)}",
+            exc_info=True,
+            extra={'request_id': getattr(g, 'request_id', 'unknown')}
+        )
+        
+        if current_app.debug:
+            raise
+            
+        generic_error = BaseApplicationException(
+            message="An unexpected error occurred",
+            code="INTERNAL_ERROR",
+            status_code=500,
+            user_message="Ein unerwarteter Fehler ist aufgetreten"
+        )
+        return _handle_error(generic_error)
+
+
+def _handle_error(error: Union[BaseApplicationException, HTTPException, Exception]) -> tuple:
+    if isinstance(error, HTTPException):
+        status_code = error.code
+        error_dict = {
+            'error': {
+                'code': error.name.upper().replace(' ', '_'),
+                'message': error.description or str(error),
+                'request_id': getattr(g, 'request_id', 'unknown')
+            }
+        }
+        user_message = error.description or str(error)
+    elif isinstance(error, BaseApplicationException):
+        status_code = error.status_code
+        error_dict = error.to_dict(include_details=current_app.debug)
+        error_dict['error']['request_id'] = getattr(g, 'request_id', error.request_id)
+        user_message = error.user_message
+        
+        logger.error(
+            f"{error.__class__.__name__}: {error.message}",
+            extra={
+                'error_code': error.code,
+                'details': error.details,
+                'request_id': error_dict['error']['request_id']
+            }
+        )
+    else:
+        status_code = 500
+        error_dict = {
+            'error': {
+                'code': 'INTERNAL_ERROR',
+                'message': 'An internal error occurred',
+                'request_id': getattr(g, 'request_id', 'unknown')
+            }
+        }
+        user_message = "Ein interner Fehler ist aufgetreten"
+    
+    if _is_json_request():
+        return jsonify(error_dict), status_code
+    else:
+        if status_code == 404:
+            return render_template('404.html'), 404
+        elif status_code >= 500:
+            return render_template('500.html', error=user_message), status_code
+        else:
+            flash(user_message, 'error')
+            return render_template('error.html', 
+                                 error=user_message,
+                                 error_code=error_dict['error']['code'],
+                                 request_id=error_dict['error']['request_id']), status_code
+
+
+def _convert_psycopg2_error(error: psycopg2.Error) -> DatabaseException:
+    error_code = getattr(error, 'pgcode', None)
+    error_message = str(error).split('\n')[0]
+    
+    if isinstance(error, psycopg2.OperationalError):
+        return ConnectionError(
+            message=f"Database connection failed: {error_message}",
+            host=None
+        )
+    elif isinstance(error, psycopg2.IntegrityError):
+        if error_code == '23505':
+            return ValidationException(
+                message="Duplicate entry violation",
+                details={'constraint': error_message},
+                user_message="Dieser Eintrag existiert bereits"
+            )
+        elif error_code == '23503':
+            return ValidationException(
+                message="Foreign key violation",
+                details={'constraint': error_message},
+                user_message="Referenzierte Daten existieren nicht"
+            )
+        else:
+            return ValidationException(
+                message="Data integrity violation",
+                details={'error_code': error_code},
+                user_message="Datenintegritätsfehler"
+            )
+    elif isinstance(error, psycopg2.DataError):
+        return ValidationException(
+            message="Invalid data format",
+            details={'error': error_message},
+            user_message="Ungültiges Datenformat"
+        )
+    else:
+        return QueryError(
+            message=error_message,
+            query="[query hidden for security]",
+            error_code=error_code
+        )
+
+
+def _is_json_request() -> bool:
+    return (request.is_json or 
+            request.path.startswith('/api/') or
+            request.accept_mimetypes.best == 'application/json')
+
+
+def handle_errors(
+    catch: tuple = (Exception,),
+    message: str = "Operation failed",
+    user_message: Optional[str] = None,
+    redirect_to: Optional[str] = None
+) -> Callable:
+    def decorator(func: Callable) -> Callable:
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            try:
+                return func(*args, **kwargs)
+            except catch as e:
+                if isinstance(e, BaseApplicationException):
+                    raise
+                    
+                logger.error(
+                    f"Error in {func.__name__}: {str(e)}",
+                    exc_info=True,
+                    extra={'request_id': getattr(g, 'request_id', 'unknown')}
+                )
+                
+                if _is_json_request():
+                    return jsonify({
+                        'error': {
+                            'code': 'OPERATION_FAILED',
+                            'message': user_message or message,
+                            'request_id': getattr(g, 'request_id', 'unknown')
+                        }
+                    }), 500
+                else:
+                    flash(user_message or message, 'error')
+                    if redirect_to:
+                        return redirect(url_for(redirect_to))
+                    return redirect(request.referrer or url_for('admin.dashboard'))
+                    
+        return wrapper
+    return decorator
+
+
+def validate_request(
+    required_fields: Optional[Dict[str, type]] = None,
+    optional_fields: Optional[Dict[str, type]] = None
+) -> Callable:
+    def decorator(func: Callable) -> Callable:
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            data = request.get_json() if request.is_json else request.form
+            
+            if required_fields:
+                for field, expected_type in required_fields.items():
+                    if field not in data:
+                        raise ValidationException(
+                            message=f"Missing required field: {field}",
+                            field=field,
+                            user_message=f"Pflichtfeld fehlt: {field}"
+                        )
+                    
+                    try:
+                        if expected_type != str:
+                            if expected_type == int:
+                                int(data[field])
+                            elif expected_type == float:
+                                float(data[field])
+                            elif expected_type == bool:
+                                if isinstance(data[field], str):
+                                    if data[field].lower() not in ['true', 'false', '1', '0']:
+                                        raise ValueError
+                    except (ValueError, TypeError):
+                        raise ValidationException(
+                            message=f"Invalid type for field {field}",
+                            field=field,
+                            value=data[field],
+                            details={'expected_type': expected_type.__name__},
+                            user_message=f"Ungültiger Typ für Feld {field}"
+                        )
+            
+            return func(*args, **kwargs)
+        return wrapper
+    return decorator
+
+
+class ErrorContext:
+    def __init__(
+        self,
+        operation: str,
+        resource_type: Optional[str] = None,
+        resource_id: Optional[Any] = None
+    ):
+        self.operation = operation
+        self.resource_type = resource_type
+        self.resource_id = resource_id
+        
+    def __enter__(self):
+        return self
+        
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        if exc_val is None:
+            return False
+            
+        if isinstance(exc_val, BaseApplicationException):
+            return False
+            
+        logger.error(
+            f"Error during {self.operation}",
+            exc_info=True,
+            extra={
+                'operation': self.operation,
+                'resource_type': self.resource_type,
+                'resource_id': self.resource_id,
+                'request_id': getattr(g, 'request_id', 'unknown')
+            }
+        )
+        
+        return False
--- a/v2_adminpanel/core/exceptions.py
+++ b/v2_adminpanel/core/exceptions.py
@@ -0,0 +1,356 @@
+import uuid
+from typing import Optional, Dict, Any
+from datetime import datetime
+
+
+class BaseApplicationException(Exception):
+    def __init__(
+        self,
+        message: str,
+        code: str,
+        status_code: int = 500,
+        details: Optional[Dict[str, Any]] = None,
+        user_message: Optional[str] = None
+    ):
+        super().__init__(message)
+        self.message = message
+        self.code = code
+        self.status_code = status_code
+        self.details = details or {}
+        self.user_message = user_message or message
+        self.timestamp = datetime.utcnow()
+        self.request_id = str(uuid.uuid4())
+    
+    def to_dict(self, include_details: bool = False) -> Dict[str, Any]:
+        result = {
+            'error': {
+                'code': self.code,
+                'message': self.user_message,
+                'timestamp': self.timestamp.isoformat(),
+                'request_id': self.request_id
+            }
+        }
+        
+        if include_details and self.details:
+            result['error']['details'] = self.details
+            
+        return result
+
+
+class ValidationException(BaseApplicationException):
+    def __init__(
+        self,
+        message: str,
+        field: Optional[str] = None,
+        value: Any = None,
+        details: Optional[Dict[str, Any]] = None,
+        user_message: Optional[str] = None
+    ):
+        details = details or {}
+        if field:
+            details['field'] = field
+        if value is not None:
+            details['value'] = str(value)
+            
+        super().__init__(
+            message=message,
+            code='VALIDATION_ERROR',
+            status_code=400,
+            details=details,
+            user_message=user_message or "Ungültige Eingabe"
+        )
+
+
+class InputValidationError(ValidationException):
+    def __init__(
+        self,
+        field: str,
+        message: str,
+        value: Any = None,
+        expected_type: Optional[str] = None
+    ):
+        details = {'expected_type': expected_type} if expected_type else None
+        super().__init__(
+            message=f"Invalid input for field '{field}': {message}",
+            field=field,
+            value=value,
+            details=details,
+            user_message=f"Ungültiger Wert für Feld '{field}'"
+        )
+
+
+class BusinessRuleViolation(ValidationException):
+    def __init__(
+        self,
+        rule: str,
+        message: str,
+        context: Optional[Dict[str, Any]] = None
+    ):
+        super().__init__(
+            message=message,
+            details={'rule': rule, 'context': context or {}},
+            user_message="Geschäftsregel verletzt"
+        )
+
+
+class DataIntegrityError(ValidationException):
+    def __init__(
+        self,
+        entity: str,
+        constraint: str,
+        message: str,
+        details: Optional[Dict[str, Any]] = None
+    ):
+        details = details or {}
+        details.update({'entity': entity, 'constraint': constraint})
+        super().__init__(
+            message=message,
+            details=details,
+            user_message="Datenintegritätsfehler"
+        )
+
+
+class AuthenticationException(BaseApplicationException):
+    def __init__(
+        self,
+        message: str,
+        details: Optional[Dict[str, Any]] = None,
+        user_message: Optional[str] = None
+    ):
+        super().__init__(
+            message=message,
+            code='AUTHENTICATION_ERROR',
+            status_code=401,
+            details=details,
+            user_message=user_message or "Authentifizierung fehlgeschlagen"
+        )
+
+
+class InvalidCredentialsError(AuthenticationException):
+    def __init__(self, username: Optional[str] = None):
+        details = {'username': username} if username else None
+        super().__init__(
+            message="Invalid username or password",
+            details=details,
+            user_message="Ungültiger Benutzername oder Passwort"
+        )
+
+
+class SessionExpiredError(AuthenticationException):
+    def __init__(self, session_id: Optional[str] = None):
+        details = {'session_id': session_id} if session_id else None
+        super().__init__(
+            message="Session has expired",
+            details=details,
+            user_message="Ihre Sitzung ist abgelaufen"
+        )
+
+
+class InsufficientPermissionsError(AuthenticationException):
+    def __init__(
+        self,
+        required_permission: str,
+        user_permissions: Optional[list] = None
+    ):
+        super().__init__(
+            message=f"User lacks required permission: {required_permission}",
+            details={
+                'required': required_permission,
+                'user_permissions': user_permissions or []
+            },
+            user_message="Unzureichende Berechtigungen für diese Aktion"
+        )
+        self.status_code = 403
+
+
+class DatabaseException(BaseApplicationException):
+    def __init__(
+        self,
+        message: str,
+        query: Optional[str] = None,
+        details: Optional[Dict[str, Any]] = None,
+        user_message: Optional[str] = None
+    ):
+        details = details or {}
+        if query:
+            details['query_hash'] = str(hash(query))
+            
+        super().__init__(
+            message=message,
+            code='DATABASE_ERROR',
+            status_code=500,
+            details=details,
+            user_message=user_message or "Datenbankfehler aufgetreten"
+        )
+
+
+class ConnectionError(DatabaseException):
+    def __init__(self, message: str, host: Optional[str] = None):
+        details = {'host': host} if host else None
+        super().__init__(
+            message=message,
+            details=details,
+            user_message="Datenbankverbindung fehlgeschlagen"
+        )
+
+
+class QueryError(DatabaseException):
+    def __init__(
+        self,
+        message: str,
+        query: str,
+        error_code: Optional[str] = None
+    ):
+        super().__init__(
+            message=message,
+            query=query,
+            details={'error_code': error_code} if error_code else None,
+            user_message="Datenbankabfrage fehlgeschlagen"
+        )
+
+
+class TransactionError(DatabaseException):
+    def __init__(self, message: str, operation: str):
+        super().__init__(
+            message=message,
+            details={'operation': operation},
+            user_message="Transaktion fehlgeschlagen"
+        )
+
+
+class ExternalServiceException(BaseApplicationException):
+    def __init__(
+        self,
+        service_name: str,
+        message: str,
+        details: Optional[Dict[str, Any]] = None,
+        user_message: Optional[str] = None
+    ):
+        details = details or {}
+        details['service'] = service_name
+        
+        super().__init__(
+            message=message,
+            code='EXTERNAL_SERVICE_ERROR',
+            status_code=502,
+            details=details,
+            user_message=user_message or f"Fehler beim Zugriff auf {service_name}"
+        )
+
+
+class APIError(ExternalServiceException):
+    def __init__(
+        self,
+        service_name: str,
+        endpoint: str,
+        status_code: int,
+        message: str
+    ):
+        super().__init__(
+            service_name=service_name,
+            message=message,
+            details={
+                'endpoint': endpoint,
+                'response_status': status_code
+            },
+            user_message=f"API-Fehler bei {service_name}"
+        )
+
+
+class TimeoutError(ExternalServiceException):
+    def __init__(
+        self,
+        service_name: str,
+        timeout_seconds: int,
+        operation: str
+    ):
+        super().__init__(
+            service_name=service_name,
+            message=f"Timeout after {timeout_seconds}s while {operation}",
+            details={
+                'timeout_seconds': timeout_seconds,
+                'operation': operation
+            },
+            user_message=f"Zeitüberschreitung bei {service_name}"
+        )
+
+
+class ResourceException(BaseApplicationException):
+    def __init__(
+        self,
+        message: str,
+        resource_type: str,
+        resource_id: Any = None,
+        details: Optional[Dict[str, Any]] = None,
+        user_message: Optional[str] = None
+    ):
+        details = details or {}
+        details.update({
+            'resource_type': resource_type,
+            'resource_id': str(resource_id) if resource_id else None
+        })
+        
+        super().__init__(
+            message=message,
+            code='RESOURCE_ERROR',
+            status_code=404,
+            details=details,
+            user_message=user_message or "Ressourcenfehler"
+        )
+
+
+class ResourceNotFoundError(ResourceException):
+    def __init__(
+        self,
+        resource_type: str,
+        resource_id: Any = None,
+        search_criteria: Optional[Dict[str, Any]] = None
+    ):
+        details = {'search_criteria': search_criteria} if search_criteria else None
+        super().__init__(
+            message=f"{resource_type} not found",
+            resource_type=resource_type,
+            resource_id=resource_id,
+            details=details,
+            user_message=f"{resource_type} nicht gefunden"
+        )
+        self.status_code = 404
+
+
+class ResourceConflictError(ResourceException):
+    def __init__(
+        self,
+        resource_type: str,
+        resource_id: Any,
+        conflict_reason: str
+    ):
+        super().__init__(
+            message=f"Conflict with {resource_type}: {conflict_reason}",
+            resource_type=resource_type,
+            resource_id=resource_id,
+            details={'conflict_reason': conflict_reason},
+            user_message=f"Konflikt mit {resource_type}"
+        )
+        self.status_code = 409
+
+
+class ResourceLimitExceeded(ResourceException):
+    def __init__(
+        self,
+        resource_type: str,
+        limit: int,
+        current: int,
+        requested: Optional[int] = None
+    ):
+        details = {
+            'limit': limit,
+            'current': current,
+            'requested': requested
+        }
+        super().__init__(
+            message=f"{resource_type} limit exceeded: {current}/{limit}",
+            resource_type=resource_type,
+            details=details,
+            user_message=f"Limit für {resource_type} überschritten"
+        )
+        self.status_code = 429
--- a/v2_adminpanel/core/logging_config.py
+++ b/v2_adminpanel/core/logging_config.py
@@ -0,0 +1,190 @@
+import logging
+import logging.handlers
+import json
+import sys
+import os
+from datetime import datetime
+from typing import Dict, Any
+from flask import g, request, has_request_context
+
+
+class StructuredFormatter(logging.Formatter):
+    def format(self, record):
+        log_data = {
+            'timestamp': datetime.utcnow().isoformat(),
+            'level': record.levelname,
+            'logger': record.name,
+            'message': record.getMessage(),
+            'module': record.module,
+            'function': record.funcName,
+            'line': record.lineno
+        }
+        
+        if has_request_context():
+            log_data['request'] = {
+                'method': request.method,
+                'path': request.path,
+                'remote_addr': request.remote_addr,
+                'user_agent': request.user_agent.string,
+                'request_id': getattr(g, 'request_id', 'unknown')
+            }
+        
+        if hasattr(record, 'request_id'):
+            log_data['request_id'] = record.request_id
+            
+        if hasattr(record, 'error_code'):
+            log_data['error_code'] = record.error_code
+            
+        if hasattr(record, 'details') and record.details:
+            log_data['details'] = self._sanitize_details(record.details)
+        
+        if record.exc_info:
+            log_data['exception'] = {
+                'type': record.exc_info[0].__name__,
+                'message': str(record.exc_info[1]),
+                'traceback': self.formatException(record.exc_info)
+            }
+        
+        return json.dumps(log_data, ensure_ascii=False)
+    
+    def _sanitize_details(self, details: Dict[str, Any]) -> Dict[str, Any]:
+        sensitive_fields = {
+            'password', 'secret', 'token', 'api_key', 'authorization',
+            'credit_card', 'ssn', 'pin'
+        }
+        
+        sanitized = {}
+        for key, value in details.items():
+            if any(field in key.lower() for field in sensitive_fields):
+                sanitized[key] = '[REDACTED]'
+            elif isinstance(value, dict):
+                sanitized[key] = self._sanitize_details(value)
+            else:
+                sanitized[key] = value
+                
+        return sanitized
+
+
+class ErrorLevelFilter(logging.Filter):
+    def __init__(self, min_level=logging.ERROR):
+        self.min_level = min_level
+    
+    def filter(self, record):
+        return record.levelno >= self.min_level
+
+
+def setup_logging(app):
+    log_level = os.getenv('LOG_LEVEL', 'INFO').upper()
+    log_dir = os.getenv('LOG_DIR', 'logs')
+    
+    os.makedirs(log_dir, exist_ok=True)
+    
+    root_logger = logging.getLogger()
+    root_logger.setLevel(getattr(logging, log_level))
+    
+    console_handler = logging.StreamHandler(sys.stdout)
+    console_handler.setLevel(logging.INFO)
+    
+    if app.debug:
+        console_formatter = logging.Formatter(
+            '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
+        )
+    else:
+        console_formatter = StructuredFormatter()
+    
+    console_handler.setFormatter(console_formatter)
+    root_logger.addHandler(console_handler)
+    
+    app_log_handler = logging.handlers.RotatingFileHandler(
+        os.path.join(log_dir, 'app.log'),
+        maxBytes=10 * 1024 * 1024,
+        backupCount=10
+    )
+    app_log_handler.setLevel(logging.DEBUG)
+    app_log_handler.setFormatter(StructuredFormatter())
+    root_logger.addHandler(app_log_handler)
+    
+    error_log_handler = logging.handlers.RotatingFileHandler(
+        os.path.join(log_dir, 'errors.log'),
+        maxBytes=10 * 1024 * 1024,
+        backupCount=10
+    )
+    error_log_handler.setLevel(logging.ERROR)
+    error_log_handler.setFormatter(StructuredFormatter())
+    error_log_handler.addFilter(ErrorLevelFilter())
+    root_logger.addHandler(error_log_handler)
+    
+    security_logger = logging.getLogger('security')
+    security_handler = logging.handlers.RotatingFileHandler(
+        os.path.join(log_dir, 'security.log'),
+        maxBytes=10 * 1024 * 1024,
+        backupCount=20
+    )
+    security_handler.setFormatter(StructuredFormatter())
+    security_logger.addHandler(security_handler)
+    security_logger.setLevel(logging.INFO)
+    
+    werkzeug_logger = logging.getLogger('werkzeug')
+    werkzeug_logger.setLevel(logging.WARNING)
+    
+    @app.before_request
+    def log_request_info():
+        logger = logging.getLogger('request')
+        logger.info(
+            'Request started',
+            extra={
+                'request_id': getattr(g, 'request_id', 'unknown'),
+                'details': {
+                    'method': request.method,
+                    'path': request.path,
+                    'query_params': dict(request.args),
+                    'content_length': request.content_length
+                }
+            }
+        )
+    
+    @app.after_request
+    def log_response_info(response):
+        logger = logging.getLogger('request')
+        logger.info(
+            'Request completed',
+            extra={
+                'request_id': getattr(g, 'request_id', 'unknown'),
+                'details': {
+                    'status_code': response.status_code,
+                    'content_length': response.content_length or 0
+                }
+            }
+        )
+        return response
+
+
+def get_logger(name: str) -> logging.Logger:
+    return logging.getLogger(name)
+
+
+def log_error(logger: logging.Logger, message: str, error: Exception = None, **kwargs):
+    extra = kwargs.copy()
+    
+    if error:
+        extra['error_type'] = type(error).__name__
+        extra['error_message'] = str(error)
+        
+        if hasattr(error, 'code'):
+            extra['error_code'] = error.code
+        if hasattr(error, 'details'):
+            extra['details'] = error.details
+            
+    logger.error(message, exc_info=error, extra=extra)
+
+
+def log_security_event(event_type: str, message: str, **details):
+    logger = logging.getLogger('security')
+    logger.warning(
+        f"Security Event: {event_type} - {message}",
+        extra={
+            'security_event': event_type,
+            'details': details,
+            'request_id': getattr(g, 'request_id', 'unknown') if has_request_context() else None
+        }
+    )
--- a/v2_adminpanel/core/monitoring.py
+++ b/v2_adminpanel/core/monitoring.py
@@ -0,0 +1,246 @@
+import time
+import functools
+from typing import Dict, Any, Optional, List
+from collections import defaultdict, deque
+from datetime import datetime, timedelta
+from threading import Lock
+import logging
+
+from prometheus_client import Counter, Histogram, Gauge, generate_latest
+from flask import g, request, Response
+
+from .exceptions import BaseApplicationException
+from .logging_config import log_security_event
+
+
+logger = logging.getLogger(__name__)
+
+
+class ErrorMetrics:
+    def __init__(self):
+        self.error_counter = Counter(
+            'app_errors_total',
+            'Total number of errors',
+            ['error_code', 'status_code', 'endpoint']
+        )
+        
+        self.error_rate = Gauge(
+            'app_error_rate',
+            'Error rate per minute',
+            ['error_code']
+        )
+        
+        self.request_duration = Histogram(
+            'app_request_duration_seconds',
+            'Request duration in seconds',
+            ['method', 'endpoint', 'status_code']
+        )
+        
+        self.validation_errors = Counter(
+            'app_validation_errors_total',
+            'Total validation errors',
+            ['field', 'endpoint']
+        )
+        
+        self.auth_failures = Counter(
+            'app_auth_failures_total',
+            'Total authentication failures',
+            ['reason', 'endpoint']
+        )
+        
+        self.db_errors = Counter(
+            'app_database_errors_total',
+            'Total database errors',
+            ['error_type', 'operation']
+        )
+        
+        self._error_history = defaultdict(lambda: deque(maxlen=60))
+        self._lock = Lock()
+        
+    def record_error(self, error: BaseApplicationException, endpoint: str = None):
+        endpoint = endpoint or request.endpoint or 'unknown'
+        
+        self.error_counter.labels(
+            error_code=error.code,
+            status_code=error.status_code,
+            endpoint=endpoint
+        ).inc()
+        
+        with self._lock:
+            self._error_history[error.code].append(datetime.utcnow())
+            self._update_error_rates()
+        
+        if error.code == 'VALIDATION_ERROR' and 'field' in error.details:
+            self.validation_errors.labels(
+                field=error.details['field'],
+                endpoint=endpoint
+            ).inc()
+        elif error.code == 'AUTHENTICATION_ERROR':
+            reason = error.__class__.__name__
+            self.auth_failures.labels(
+                reason=reason,
+                endpoint=endpoint
+            ).inc()
+        elif error.code == 'DATABASE_ERROR':
+            error_type = error.__class__.__name__
+            operation = error.details.get('operation', 'unknown')
+            self.db_errors.labels(
+                error_type=error_type,
+                operation=operation
+            ).inc()
+    
+    def _update_error_rates(self):
+        now = datetime.utcnow()
+        one_minute_ago = now - timedelta(minutes=1)
+        
+        for error_code, timestamps in self._error_history.items():
+            recent_count = sum(1 for ts in timestamps if ts >= one_minute_ago)
+            self.error_rate.labels(error_code=error_code).set(recent_count)
+
+
+class AlertManager:
+    def __init__(self):
+        self.alerts = []
+        self.alert_thresholds = {
+            'error_rate': 10,
+            'auth_failure_rate': 5,
+            'db_error_rate': 3,
+            'response_time_95th': 2.0
+        }
+        self._lock = Lock()
+        
+    def check_alerts(self, metrics: ErrorMetrics):
+        new_alerts = []
+        
+        for error_code, rate in self._get_current_error_rates(metrics).items():
+            if rate > self.alert_thresholds['error_rate']:
+                new_alerts.append({
+                    'type': 'high_error_rate',
+                    'severity': 'critical',
+                    'error_code': error_code,
+                    'rate': rate,
+                    'threshold': self.alert_thresholds['error_rate'],
+                    'message': f'High error rate for {error_code}: {rate}/min',
+                    'timestamp': datetime.utcnow()
+                })
+        
+        auth_failure_rate = self._get_auth_failure_rate(metrics)
+        if auth_failure_rate > self.alert_thresholds['auth_failure_rate']:
+            new_alerts.append({
+                'type': 'auth_failures',
+                'severity': 'warning',
+                'rate': auth_failure_rate,
+                'threshold': self.alert_thresholds['auth_failure_rate'],
+                'message': f'High authentication failure rate: {auth_failure_rate}/min',
+                'timestamp': datetime.utcnow()
+            })
+            
+            log_security_event(
+                'HIGH_AUTH_FAILURE_RATE',
+                f'Authentication failure rate exceeded threshold',
+                rate=auth_failure_rate,
+                threshold=self.alert_thresholds['auth_failure_rate']
+            )
+        
+        with self._lock:
+            self.alerts.extend(new_alerts)
+            self.alerts = [a for a in self.alerts 
+                         if a['timestamp'] > datetime.utcnow() - timedelta(hours=24)]
+        
+        return new_alerts
+    
+    def _get_current_error_rates(self, metrics: ErrorMetrics) -> Dict[str, float]:
+        rates = {}
+        with metrics._lock:
+            now = datetime.utcnow()
+            one_minute_ago = now - timedelta(minutes=1)
+            
+            for error_code, timestamps in metrics._error_history.items():
+                rates[error_code] = sum(1 for ts in timestamps if ts >= one_minute_ago)
+        
+        return rates
+    
+    def _get_auth_failure_rate(self, metrics: ErrorMetrics) -> float:
+        return sum(
+            sample.value 
+            for sample in metrics.auth_failures._child_samples()
+        ) / 60.0
+    
+    def get_active_alerts(self) -> List[Dict[str, Any]]:
+        with self._lock:
+            return list(self.alerts)
+
+
+error_metrics = ErrorMetrics()
+alert_manager = AlertManager()
+
+
+def init_monitoring(app):
+    @app.before_request
+    def before_request():
+        g.start_time = time.time()
+    
+    @app.after_request
+    def after_request(response):
+        if hasattr(g, 'start_time'):
+            duration = time.time() - g.start_time
+            error_metrics.request_duration.labels(
+                method=request.method,
+                endpoint=request.endpoint or 'unknown',
+                status_code=response.status_code
+            ).observe(duration)
+        
+        return response
+    
+    @app.route('/metrics')
+    def metrics():
+        alert_manager.check_alerts(error_metrics)
+        return Response(generate_latest(), mimetype='text/plain')
+    
+    @app.route('/api/alerts')
+    def get_alerts():
+        alerts = alert_manager.get_active_alerts()
+        return {
+            'alerts': alerts,
+            'total': len(alerts),
+            'critical': len([a for a in alerts if a['severity'] == 'critical']),
+            'warning': len([a for a in alerts if a['severity'] == 'warning'])
+        }
+
+
+def monitor_performance(func):
+    @functools.wraps(func)
+    def wrapper(*args, **kwargs):
+        start_time = time.time()
+        
+        try:
+            result = func(*args, **kwargs)
+            return result
+        finally:
+            duration = time.time() - start_time
+            if duration > 1.0:
+                logger.warning(
+                    f"Slow function execution: {func.__name__}",
+                    extra={
+                        'function': func.__name__,
+                        'duration': duration,
+                        'request_id': getattr(g, 'request_id', 'unknown')
+                    }
+                )
+    
+    return wrapper
+
+
+def track_error(error: BaseApplicationException):
+    error_metrics.record_error(error)
+    
+    if error.status_code >= 500:
+        logger.error(
+            f"Critical error occurred: {error.code}",
+            extra={
+                'error_code': error.code,
+                'message': error.message,
+                'details': error.details,
+                'request_id': error.request_id
+            }
+        )
--- a/v2_adminpanel/core/validators.py
+++ b/v2_adminpanel/core/validators.py
@@ -0,0 +1,435 @@
+import re
+from typing import Any, Optional, List, Dict, Callable, Union
+from datetime import datetime, date
+from functools import wraps
+import ipaddress
+from flask import request
+
+from .exceptions import InputValidationError, ValidationException
+
+
+class ValidationRules:
+    EMAIL_PATTERN = re.compile(
+        r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
+    )
+    
+    PHONE_PATTERN = re.compile(
+        r'^[\+]?[(]?[0-9]{1,4}[)]?[-\s\.]?[(]?[0-9]{1,4}[)]?[-\s\.]?[0-9]{1,10}$'
+    )
+    
+    LICENSE_KEY_PATTERN = re.compile(
+        r'^[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{4}$'
+    )
+    
+    SAFE_STRING_PATTERN = re.compile(
+        r'^[a-zA-Z0-9\s\-\_\.\,\!\?\@\#\$\%\&\*\(\)\[\]\{\}\:\;\'\"\+\=\/\\]+$'
+    )
+    
+    USERNAME_PATTERN = re.compile(
+        r'^[a-zA-Z0-9_\-\.]{3,50}$'
+    )
+    
+    PASSWORD_MIN_LENGTH = 8
+    PASSWORD_REQUIRE_UPPER = True
+    PASSWORD_REQUIRE_LOWER = True
+    PASSWORD_REQUIRE_DIGIT = True
+    PASSWORD_REQUIRE_SPECIAL = True
+
+
+class Validators:
+    @staticmethod
+    def required(value: Any, field_name: str = "field") -> Any:
+        if value is None or (isinstance(value, str) and not value.strip()):
+            raise InputValidationError(
+                field=field_name,
+                message="This field is required",
+                value=value
+            )
+        return value
+    
+    @staticmethod
+    def email(value: str, field_name: str = "email") -> str:
+        value = Validators.required(value, field_name).strip()
+        
+        if not ValidationRules.EMAIL_PATTERN.match(value):
+            raise InputValidationError(
+                field=field_name,
+                message="Invalid email format",
+                value=value,
+                expected_type="email"
+            )
+        
+        return value.lower()
+    
+    @staticmethod
+    def phone(value: str, field_name: str = "phone") -> str:
+        value = Validators.required(value, field_name).strip()
+        
+        cleaned = re.sub(r'[\s\-\(\)]', '', value)
+        
+        if not ValidationRules.PHONE_PATTERN.match(value):
+            raise InputValidationError(
+                field=field_name,
+                message="Invalid phone number format",
+                value=value,
+                expected_type="phone"
+            )
+        
+        return cleaned
+    
+    @staticmethod
+    def license_key(value: str, field_name: str = "license_key") -> str:
+        value = Validators.required(value, field_name).strip().upper()
+        
+        if not ValidationRules.LICENSE_KEY_PATTERN.match(value):
+            raise InputValidationError(
+                field=field_name,
+                message="Invalid license key format (expected: XXXX-XXXX-XXXX-XXXX)",
+                value=value,
+                expected_type="license_key"
+            )
+        
+        return value
+    
+    @staticmethod
+    def integer(
+        value: Union[str, int], 
+        field_name: str = "field",
+        min_value: Optional[int] = None,
+        max_value: Optional[int] = None
+    ) -> int:
+        try:
+            int_value = int(value)
+        except (ValueError, TypeError):
+            raise InputValidationError(
+                field=field_name,
+                message="Must be a valid integer",
+                value=value,
+                expected_type="integer"
+            )
+        
+        if min_value is not None and int_value < min_value:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Must be at least {min_value}",
+                value=int_value
+            )
+        
+        if max_value is not None and int_value > max_value:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Must be at most {max_value}",
+                value=int_value
+            )
+        
+        return int_value
+    
+    @staticmethod
+    def float_number(
+        value: Union[str, float],
+        field_name: str = "field",
+        min_value: Optional[float] = None,
+        max_value: Optional[float] = None
+    ) -> float:
+        try:
+            float_value = float(value)
+        except (ValueError, TypeError):
+            raise InputValidationError(
+                field=field_name,
+                message="Must be a valid number",
+                value=value,
+                expected_type="float"
+            )
+        
+        if min_value is not None and float_value < min_value:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Must be at least {min_value}",
+                value=float_value
+            )
+        
+        if max_value is not None and float_value > max_value:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Must be at most {max_value}",
+                value=float_value
+            )
+        
+        return float_value
+    
+    @staticmethod
+    def boolean(value: Union[str, bool], field_name: str = "field") -> bool:
+        if isinstance(value, bool):
+            return value
+        
+        if isinstance(value, str):
+            value_lower = value.lower()
+            if value_lower in ['true', '1', 'yes', 'on']:
+                return True
+            elif value_lower in ['false', '0', 'no', 'off']:
+                return False
+        
+        raise InputValidationError(
+            field=field_name,
+            message="Must be a valid boolean",
+            value=value,
+            expected_type="boolean"
+        )
+    
+    @staticmethod
+    def string(
+        value: str,
+        field_name: str = "field",
+        min_length: Optional[int] = None,
+        max_length: Optional[int] = None,
+        pattern: Optional[re.Pattern] = None,
+        safe_only: bool = False
+    ) -> str:
+        value = Validators.required(value, field_name).strip()
+        
+        if min_length is not None and len(value) < min_length:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Must be at least {min_length} characters",
+                value=value
+            )
+        
+        if max_length is not None and len(value) > max_length:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Must be at most {max_length} characters",
+                value=value
+            )
+        
+        if safe_only and not ValidationRules.SAFE_STRING_PATTERN.match(value):
+            raise InputValidationError(
+                field=field_name,
+                message="Contains invalid characters",
+                value=value
+            )
+        
+        if pattern and not pattern.match(value):
+            raise InputValidationError(
+                field=field_name,
+                message="Does not match required format",
+                value=value
+            )
+        
+        return value
+    
+    @staticmethod
+    def username(value: str, field_name: str = "username") -> str:
+        value = Validators.required(value, field_name).strip()
+        
+        if not ValidationRules.USERNAME_PATTERN.match(value):
+            raise InputValidationError(
+                field=field_name,
+                message="Username must be 3-50 characters and contain only letters, numbers, _, -, or .",
+                value=value,
+                expected_type="username"
+            )
+        
+        return value
+    
+    @staticmethod
+    def password(value: str, field_name: str = "password") -> str:
+        value = Validators.required(value, field_name)
+        
+        errors = []
+        
+        if len(value) < ValidationRules.PASSWORD_MIN_LENGTH:
+            errors.append(f"at least {ValidationRules.PASSWORD_MIN_LENGTH} characters")
+        
+        if ValidationRules.PASSWORD_REQUIRE_UPPER and not re.search(r'[A-Z]', value):
+            errors.append("at least one uppercase letter")
+        
+        if ValidationRules.PASSWORD_REQUIRE_LOWER and not re.search(r'[a-z]', value):
+            errors.append("at least one lowercase letter")
+        
+        if ValidationRules.PASSWORD_REQUIRE_DIGIT and not re.search(r'\d', value):
+            errors.append("at least one digit")
+        
+        if ValidationRules.PASSWORD_REQUIRE_SPECIAL and not re.search(r'[!@#$%^&*(),.?":{}|<>]', value):
+            errors.append("at least one special character")
+        
+        if errors:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Password must contain {', '.join(errors)}",
+                value="[hidden]"
+            )
+        
+        return value
+    
+    @staticmethod
+    def date_string(
+        value: str,
+        field_name: str = "date",
+        format: str = "%Y-%m-%d",
+        min_date: Optional[date] = None,
+        max_date: Optional[date] = None
+    ) -> date:
+        value = Validators.required(value, field_name).strip()
+        
+        try:
+            date_value = datetime.strptime(value, format).date()
+        except ValueError:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Invalid date format (expected: {format})",
+                value=value,
+                expected_type="date"
+            )
+        
+        if min_date and date_value < min_date:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Date must be after {min_date}",
+                value=value
+            )
+        
+        if max_date and date_value > max_date:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Date must be before {max_date}",
+                value=value
+            )
+        
+        return date_value
+    
+    @staticmethod
+    def ip_address(
+        value: str,
+        field_name: str = "ip_address",
+        version: Optional[int] = None
+    ) -> str:
+        value = Validators.required(value, field_name).strip()
+        
+        try:
+            ip = ipaddress.ip_address(value)
+            if version and ip.version != version:
+                raise ValueError
+        except ValueError:
+            version_str = f"IPv{version}" if version else "IP"
+            raise InputValidationError(
+                field=field_name,
+                message=f"Invalid {version_str} address",
+                value=value,
+                expected_type="ip_address"
+            )
+        
+        return str(ip)
+    
+    @staticmethod
+    def url(
+        value: str,
+        field_name: str = "url",
+        require_https: bool = False
+    ) -> str:
+        value = Validators.required(value, field_name).strip()
+        
+        url_pattern = re.compile(
+            r'^https?://'
+            r'(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+[A-Z]{2,6}\.?|'
+            r'localhost|'
+            r'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})'
+            r'(?::\d+)?'
+            r'(?:/?|[/?]\S+)$', re.IGNORECASE
+        )
+        
+        if not url_pattern.match(value):
+            raise InputValidationError(
+                field=field_name,
+                message="Invalid URL format",
+                value=value,
+                expected_type="url"
+            )
+        
+        if require_https and not value.startswith('https://'):
+            raise InputValidationError(
+                field=field_name,
+                message="URL must use HTTPS",
+                value=value
+            )
+        
+        return value
+    
+    @staticmethod
+    def enum(
+        value: Any,
+        field_name: str,
+        allowed_values: List[Any]
+    ) -> Any:
+        if value not in allowed_values:
+            raise InputValidationError(
+                field=field_name,
+                message=f"Must be one of: {', '.join(map(str, allowed_values))}",
+                value=value
+            )
+        
+        return value
+
+
+def validate(rules: Dict[str, Dict[str, Any]]) -> Callable:
+    def decorator(func: Callable) -> Callable:
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            data = request.get_json() if request.is_json else request.form
+            validated_data = {}
+            
+            for field_name, field_rules in rules.items():
+                value = data.get(field_name)
+                
+                if 'required' in field_rules and field_rules['required']:
+                    value = Validators.required(value, field_name)
+                elif value is None or value == '':
+                    if 'default' in field_rules:
+                        validated_data[field_name] = field_rules['default']
+                    continue
+                
+                validator_name = field_rules.get('type', 'string')
+                validator_func = getattr(Validators, validator_name, None)
+                
+                if not validator_func:
+                    raise ValueError(f"Unknown validator type: {validator_name}")
+                
+                validator_params = {
+                    k: v for k, v in field_rules.items() 
+                    if k not in ['type', 'required', 'default']
+                }
+                validator_params['field_name'] = field_name
+                
+                validated_data[field_name] = validator_func(value, **validator_params)
+            
+            request.validated_data = validated_data
+            return func(*args, **kwargs)
+        
+        return wrapper
+    return decorator
+
+
+def sanitize_html(value: str) -> str:
+    dangerous_tags = re.compile(
+        r'<(script|iframe|object|embed|form|input|button|textarea|select|link|meta|style).*?>.*?</\1>',
+        re.IGNORECASE | re.DOTALL
+    )
+    dangerous_attrs = re.compile(
+        r'\s*(on\w+|style|javascript:)[\s]*=[\s]*["\']?[^"\'>\s]+',
+        re.IGNORECASE
+    )
+    
+    value = dangerous_tags.sub('', value)
+    value = dangerous_attrs.sub('', value)
+    
+    return value
+
+
+def sanitize_sql_identifier(value: str) -> str:
+    if not re.match(r'^[a-zA-Z_][a-zA-Z0-9_]*$', value):
+        raise ValidationException(
+            message="Invalid SQL identifier",
+            details={'value': value},
+            user_message="Ungültiger Bezeichner"
+        )
+    
+    return value
--- a/v2_adminpanel/middleware/init.py
+++ b/v2_adminpanel/middleware/init.py
@@ -0,0 +1 @@
+from .error_middleware import ErrorHandlingMiddleware
--- a/v2_adminpanel/middleware/error_middleware.py
+++ b/v2_adminpanel/middleware/error_middleware.py
@@ -0,0 +1,54 @@
+import time
+import uuid
+from typing import Optional
+from flask import request, g
+from werkzeug.exceptions import HTTPException
+
+from core.exceptions import BaseApplicationException
+from core.monitoring import track_error
+from core.logging_config import get_logger
+
+
+logger = get_logger(__name__)
+
+
+class ErrorHandlingMiddleware:
+    def __init__(self, app=None):
+        self.app = app
+        if app:
+            self.init_app(app)
+    
+    def init_app(self, app):
+        app.before_request(self._before_request)
+        app.teardown_appcontext(self._teardown_request)
+        
+    def _before_request(self):
+        g.request_id = request.headers.get('X-Request-ID', str(uuid.uuid4()))
+        g.start_time = time.time()
+        g.errors = []
+        
+    def _teardown_request(self, exception=None):
+        if exception:
+            self._handle_exception(exception)
+            
+        if hasattr(g, 'errors') and g.errors:
+            for error in g.errors:
+                if isinstance(error, BaseApplicationException):
+                    track_error(error)
+    
+    def _handle_exception(self, exception):
+        if isinstance(exception, BaseApplicationException):
+            track_error(exception)
+        elif isinstance(exception, HTTPException):
+            pass
+        else:
+            logger.error(
+                f"Unhandled exception: {type(exception).__name__}",
+                exc_info=True,
+                extra={
+                    'request_id': getattr(g, 'request_id', 'unknown'),
+                    'endpoint': request.endpoint,
+                    'method': request.method,
+                    'path': request.path
+                }
+            )
--- a/v2_adminpanel/requirements.txt
+++ b/v2_adminpanel/requirements.txt
@@ -14,3 +14,4 @@ pyotp
 qrcode[pil]
 PyJWT
 prometheus-flask-exporter
+prometheus-client
--- a/v2_adminpanel/templates/500.html
+++ b/v2_adminpanel/templates/500.html
@@ -5,13 +5,40 @@
 {% block content %}
 <div class="container mt-5">
    <div class="row justify-content-center">
-        <div class="col-md-6">
-            <div class="card">
-                <div class="card-body text-center">
-                    <h1 class="display-1">500</h1>
-                    <h2>Interner Serverfehler</h2>
-                    <p>Es ist ein Fehler aufgetreten. Bitte versuchen Sie es später erneut.</p>
-                    <a href="{{ url_for('admin.dashboard') }}" class="btn btn-primary">Zur Startseite</a>
+        <div class="col-md-8">
+            <div class="card shadow-lg">
+                <div class="card-body text-center py-5">
+                    <div class="mb-4">
+                        <i class="bi bi-exclamation-octagon text-danger" style="font-size: 4rem;"></i>
+                    </div>
+                    <h1 class="display-1 text-danger">500</h1>
+                    <h2 class="mb-4">Interner Serverfehler</h2>
+                    <p class="lead mb-4">
+                        Es tut uns leid, aber es ist ein unerwarteter Fehler aufgetreten.
+                        Unser Team wurde benachrichtigt und arbeitet an einer Lösung.
+                    </p>
+                    
+                    {% if error %}
+                    <div class="alert alert-warning text-start mx-auto" style="max-width: 500px;">
+                        <p class="mb-0"><strong>Fehlermeldung:</strong> {{ error }}</p>
+                    </div>
+                    {% endif %}
+                    
+                    <div class="mt-4">
+                        <a href="{{ url_for('admin.dashboard') }}" class="btn btn-primary btn-lg">
+                            <i class="bi bi-house"></i> Zum Dashboard
+                        </a>
+                        <button onclick="location.reload();" class="btn btn-outline-secondary btn-lg ms-2">
+                            <i class="bi bi-arrow-clockwise"></i> Seite neu laden
+                        </button>
+                    </div>
+                    
+                    <div class="mt-5 text-muted">
+                        <small>
+                            Fehler-ID: <code>{{ request_id or 'Nicht verfügbar' }}</code><br>
+                            Zeitstempel: {{ timestamp or 'Nicht verfügbar' }}
+                        </small>
+                    </div>
                </div>
            </div>
        </div>
--- a/v2_adminpanel/templates/error.html
+++ b/v2_adminpanel/templates/error.html
@@ -6,28 +6,46 @@
 <div class="container">
    <div class="row justify-content-center mt-5">
        <div class="col-md-8">
-            <div class="card">
+            <div class="card shadow">
                <div class="card-header bg-danger text-white">
                    <h4 class="mb-0">
                        <i class="bi bi-exclamation-triangle-fill"></i> 
-                        {{ error_message|default('Ein Fehler ist aufgetreten') }}
+                        Fehler
                    </h4>
                </div>
                <div class="card-body">
-                    {% if details %}
-                    <div class="alert alert-danger">
-                        <h6>Details:</h6>
-                        <pre class="mb-0">{{ details }}</pre>
+                    <div class="alert alert-danger mb-4" role="alert">
+                        <h5 class="alert-heading">{{ error|default('Ein Fehler ist aufgetreten') }}</h5>
+                        {% if error_code %}
+                        <hr>
+                        <p class="mb-0">
+                            <strong>Fehlercode:</strong> {{ error_code }}<br>
+                            {% if request_id %}
+                            <strong>Anfrage-ID:</strong> <code>{{ request_id }}</code>
+                            {% endif %}
+                        </p>
+                        {% endif %}
                    </div>
-                    {% endif %}
                    
-                    <div class="mt-3">
+                    <div class="bg-light p-3 rounded mb-4">
+                        <h6 class="text-muted">Was können Sie tun?</h6>
+                        <ul class="mb-0">
+                            <li>Versuchen Sie die Aktion erneut</li>
+                            <li>Überprüfen Sie Ihre Eingaben</li>
+                            <li>Kontaktieren Sie den Support mit der Anfrage-ID</li>
+                        </ul>
+                    </div>
+                    
+                    <div class="d-flex gap-2">
                        <a href="{{ url_for('admin.dashboard') }}" class="btn btn-primary">
-                            <i class="bi bi-house"></i> Zurück zum Dashboard
+                            <i class="bi bi-house"></i> Zum Dashboard
                        </a>
                        <button onclick="window.history.back();" class="btn btn-secondary">
                            <i class="bi bi-arrow-left"></i> Zurück
                        </button>
+                        <button onclick="location.reload();" class="btn btn-outline-secondary">
+                            <i class="bi bi-arrow-clockwise"></i> Erneut versuchen
+                        </button>
                    </div>
                </div>
            </div>
--- a/v2_adminpanel/tests/init.py
+++ b/v2_adminpanel/tests/init.py
--- a/v2_adminpanel/tests/test_error_handling.py
+++ b/v2_adminpanel/tests/test_error_handling.py
@@ -0,0 +1,350 @@
+import pytest
+import json
+from datetime import datetime
+from flask import Flask, request
+from werkzeug.exceptions import NotFound
+
+from ..core.exceptions import (
+    ValidationException, InputValidationError, AuthenticationException,
+    InvalidCredentialsError, DatabaseException, QueryError,
+    ResourceNotFoundError, BusinessRuleViolation
+)
+from ..core.error_handlers import init_error_handlers, handle_errors, validate_request
+from ..core.validators import Validators, validate
+from ..core.monitoring import error_metrics, alert_manager
+from ..middleware.error_middleware import ErrorHandlingMiddleware
+
+
+@pytest.fixture
+def app():
+    app = Flask(__name__)
+    app.config['TESTING'] = True
+    app.config['SECRET_KEY'] = 'test-secret-key'
+    
+    init_error_handlers(app)
+    ErrorHandlingMiddleware(app)
+    
+    @app.route('/test-validation-error')
+    def test_validation_error():
+        raise InputValidationError(
+            field='email',
+            message='Invalid email format',
+            value='not-an-email'
+        )
+    
+    @app.route('/test-auth-error')
+    def test_auth_error():
+        raise InvalidCredentialsError('testuser')
+    
+    @app.route('/test-db-error')
+    def test_db_error():
+        raise QueryError(
+            message='Column not found',
+            query='SELECT * FROM users',
+            error_code='42703'
+        )
+    
+    @app.route('/test-not-found')
+    def test_not_found():
+        raise ResourceNotFoundError('User', 123)
+    
+    @app.route('/test-generic-error')
+    def test_generic_error():
+        raise Exception('Something went wrong')
+    
+    @app.route('/test-validate', methods=['POST'])
+    @validate({
+        'email': {'type': 'email', 'required': True},
+        'age': {'type': 'integer', 'required': True, 'min_value': 18},
+        'username': {'type': 'username', 'required': False}
+    })
+    def test_validate():
+        return {'success': True, 'data': request.validated_data}
+    
+    @app.route('/test-handle-errors')
+    @handle_errors(
+        catch=(ValueError,),
+        message='Value error occurred',
+        user_message='Ungültiger Wert'
+    )
+    def test_handle_errors():
+        raise ValueError('Invalid value')
+    
+    return app
+
+
+@pytest.fixture
+def client(app):
+    return app.test_client()
+
+
+class TestExceptions:
+    def test_validation_exception(self):
+        exc = ValidationException(
+            message='Test validation error',
+            field='test_field',
+            value='test_value',
+            user_message='Test user message'
+        )
+        
+        assert exc.code == 'VALIDATION_ERROR'
+        assert exc.status_code == 400
+        assert exc.details['field'] == 'test_field'
+        assert exc.details['value'] == 'test_value'
+        assert exc.user_message == 'Test user message'
+    
+    def test_input_validation_error(self):
+        exc = InputValidationError(
+            field='email',
+            message='Invalid format',
+            value='not-email',
+            expected_type='email'
+        )
+        
+        assert exc.code == 'VALIDATION_ERROR'
+        assert exc.status_code == 400
+        assert exc.details['field'] == 'email'
+        assert exc.details['expected_type'] == 'email'
+    
+    def test_business_rule_violation(self):
+        exc = BusinessRuleViolation(
+            rule='max_licenses',
+            message='License limit exceeded',
+            context={'current': 10, 'max': 5}
+        )
+        
+        assert exc.details['rule'] == 'max_licenses'
+        assert exc.details['context']['current'] == 10
+    
+    def test_authentication_exceptions(self):
+        exc = InvalidCredentialsError('testuser')
+        assert exc.status_code == 401
+        assert exc.details['username'] == 'testuser'
+    
+    def test_database_exceptions(self):
+        exc = QueryError(
+            message='Syntax error',
+            query='SELECT * FORM users',
+            error_code='42601'
+        )
+        
+        assert exc.code == 'DATABASE_ERROR'
+        assert exc.status_code == 500
+        assert 'query_hash' in exc.details
+        assert exc.details['error_code'] == '42601'
+    
+    def test_resource_not_found(self):
+        exc = ResourceNotFoundError(
+            resource_type='License',
+            resource_id='ABC123',
+            search_criteria={'customer_id': 1}
+        )
+        
+        assert exc.status_code == 404
+        assert exc.details['resource_type'] == 'License'
+        assert exc.details['resource_id'] == 'ABC123'
+        assert exc.details['search_criteria']['customer_id'] == 1
+
+
+class TestErrorHandlers:
+    def test_validation_error_json_response(self, client):
+        response = client.get(
+            '/test-validation-error',
+            headers={'Accept': 'application/json'}
+        )
+        
+        assert response.status_code == 400
+        data = json.loads(response.data)
+        assert 'error' in data
+        assert data['error']['code'] == 'VALIDATION_ERROR'
+        assert 'request_id' in data['error']
+    
+    def test_validation_error_html_response(self, client):
+        response = client.get('/test-validation-error')
+        
+        assert response.status_code == 400
+        assert b'Ungültiger Wert für Feld' in response.data
+    
+    def test_auth_error_response(self, client):
+        response = client.get(
+            '/test-auth-error',
+            headers={'Accept': 'application/json'}
+        )
+        
+        assert response.status_code == 401
+        data = json.loads(response.data)
+        assert data['error']['code'] == 'AUTHENTICATION_ERROR'
+    
+    def test_db_error_response(self, client):
+        response = client.get(
+            '/test-db-error',
+            headers={'Accept': 'application/json'}
+        )
+        
+        assert response.status_code == 500
+        data = json.loads(response.data)
+        assert data['error']['code'] == 'DATABASE_ERROR'
+    
+    def test_not_found_response(self, client):
+        response = client.get('/test-not-found')
+        
+        assert response.status_code == 404
+        assert b'User nicht gefunden' in response.data
+    
+    def test_generic_error_response(self, client):
+        response = client.get(
+            '/test-generic-error',
+            headers={'Accept': 'application/json'}
+        )
+        
+        assert response.status_code == 500
+        data = json.loads(response.data)
+        assert data['error']['code'] == 'INTERNAL_ERROR'
+    
+    def test_validate_decorator_success(self, client):
+        response = client.post(
+            '/test-validate',
+            json={'email': 'test@example.com', 'age': 25, 'username': 'testuser'}
+        )
+        
+        assert response.status_code == 200
+        data = json.loads(response.data)
+        assert data['success'] is True
+        assert data['data']['email'] == 'test@example.com'
+        assert data['data']['age'] == 25
+    
+    def test_validate_decorator_failure(self, client):
+        response = client.post(
+            '/test-validate',
+            json={'email': 'invalid-email', 'age': 15}
+        )
+        
+        assert response.status_code == 400
+        data = json.loads(response.data)
+        assert data['error']['code'] == 'VALIDATION_ERROR'
+    
+    def test_handle_errors_decorator(self, client):
+        response = client.get('/test-handle-errors')
+        
+        assert response.status_code == 500
+        assert b'Ungültiger Wert' in response.data
+
+
+class TestValidators:
+    def test_email_validator(self):
+        assert Validators.email('test@example.com') == 'test@example.com'
+        assert Validators.email('TEST@EXAMPLE.COM') == 'test@example.com'
+        
+        with pytest.raises(InputValidationError):
+            Validators.email('invalid-email')
+        
+        with pytest.raises(InputValidationError):
+            Validators.email('')
+    
+    def test_phone_validator(self):
+        assert Validators.phone('+1-234-567-8900') == '+12345678900'
+        assert Validators.phone('(123) 456-7890') == '1234567890'
+        
+        with pytest.raises(InputValidationError):
+            Validators.phone('123')
+    
+    def test_license_key_validator(self):
+        assert Validators.license_key('abcd-1234-efgh-5678') == 'ABCD-1234-EFGH-5678'
+        
+        with pytest.raises(InputValidationError):
+            Validators.license_key('invalid-key')
+    
+    def test_integer_validator(self):
+        assert Validators.integer('123') == 123
+        assert Validators.integer(456) == 456
+        assert Validators.integer('10', min_value=5, max_value=15) == 10
+        
+        with pytest.raises(InputValidationError):
+            Validators.integer('abc')
+        
+        with pytest.raises(InputValidationError):
+            Validators.integer('3', min_value=5)
+        
+        with pytest.raises(InputValidationError):
+            Validators.integer('20', max_value=15)
+    
+    def test_string_validator(self):
+        assert Validators.string('test', min_length=2, max_length=10) == 'test'
+        
+        with pytest.raises(InputValidationError):
+            Validators.string('a', min_length=2)
+        
+        with pytest.raises(InputValidationError):
+            Validators.string('a' * 20, max_length=10)
+        
+        with pytest.raises(InputValidationError):
+            Validators.string('test<script>', safe_only=True)
+    
+    def test_password_validator(self):
+        assert Validators.password('Test123!@#') == 'Test123!@#'
+        
+        with pytest.raises(InputValidationError) as exc:
+            Validators.password('weak')
+        assert 'at least 8 characters' in str(exc.value)
+        
+        with pytest.raises(InputValidationError) as exc:
+            Validators.password('alllowercase123!')
+        assert 'uppercase letter' in str(exc.value)
+    
+    def test_ip_address_validator(self):
+        assert Validators.ip_address('192.168.1.1') == '192.168.1.1'
+        assert Validators.ip_address('::1') == '::1'
+        
+        with pytest.raises(InputValidationError):
+            Validators.ip_address('999.999.999.999')
+        
+        with pytest.raises(InputValidationError):
+            Validators.ip_address('::1', version=4)
+    
+    def test_url_validator(self):
+        assert Validators.url('http://example.com') == 'http://example.com'
+        assert Validators.url('https://example.com/path') == 'https://example.com/path'
+        
+        with pytest.raises(InputValidationError):
+            Validators.url('not-a-url')
+        
+        with pytest.raises(InputValidationError):
+            Validators.url('http://example.com', require_https=True)
+    
+    def test_enum_validator(self):
+        assert Validators.enum('active', 'status', ['active', 'inactive']) == 'active'
+        
+        with pytest.raises(InputValidationError):
+            Validators.enum('pending', 'status', ['active', 'inactive'])
+
+
+class TestMonitoring:
+    def test_error_metrics_recording(self, client):
+        initial_count = error_metrics.error_counter._value._value
+        
+        client.get('/test-validation-error')
+        
+        new_count = error_metrics.error_counter._value._value
+        assert new_count > initial_count
+    
+    def test_alert_generation(self):
+        for i in range(15):
+            error = ValidationException(
+                message=f'Test error {i}',
+                code='TEST_ERROR'
+            )
+            error_metrics.record_error(error, 'test_endpoint')
+        
+        alerts = alert_manager.check_alerts(error_metrics)
+        assert any(a['type'] == 'high_error_rate' for a in alerts)
+    
+    def test_metrics_endpoint(self, client):
+        response = client.get('/metrics')
+        
+        assert response.status_code == 200
+        assert b'app_errors_total' in response.data
+        assert b'app_request_duration_seconds' in response.data
+
+
+if __name__ == '__main__':
+    pytest.main([__file__, '-v'])
				`@@ -0,0 +1 @@`
				`from .error_middleware import ErrorHandlingMiddleware`