error_handling

fastmcp.server.middleware.error_handling

Error handling middleware for consistent error responses and tracking.

Classes

ErrorHandlingMiddleware

Middleware that provides consistent error handling and logging.

Catches exceptions, logs them appropriately, and converts them to proper MCP error responses. Also tracks error patterns for monitoring.

Methods:

on_message

on_message(self, context: MiddlewareContext, call_next: CallNext) -> Any

Handle errors for all messages.

get_error_stats

get_error_stats(self) -> dict[str, int]

Get error statistics for monitoring.

RetryMiddleware

Middleware that implements automatic retry logic for failed requests.

Retries requests that fail with transient errors, using exponential backoff to avoid overwhelming the server or external dependencies.

Methods:

on_request

on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any

Implement retry logic for requests.