> ## Documentation Index
> Fetch the complete documentation index at: https://gofastmcp.com/llms.txt
> Use this file to discover all available pages before exploring further.
# 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`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_message(self, context: MiddlewareContext, call_next: CallNext) -> Any
```
Handle errors for all messages.
#### `get_error_stats`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
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`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any
```
Implement retry logic for requests.