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fastmcp.server.middleware.error_handling

Error handling middleware for consistent error responses and tracking.

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Classes

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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:

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on_message 

on_message(self, context: MiddlewareContext, call_next: CallNext) -> Any
Handle errors for all messages.

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get_error_stats 

get_error_stats(self) -> dict[str, int]
Get error statistics for monitoring.

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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:

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on_request 

on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any
Implement retry logic for requests.