# Error Codes

URL: /docs/reference/errors/
Section: reference
Tags: reference, errors

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Milo uses a structured error hierarchy with namespaced error codes for precise debugging. Error hierarchy graph TB ME[MiloError] --> IE[InputError] ME --> SE[StateError] ME --> FE[FormError] ME --> AE[AppError] ME --> FLE[FlowError] ME --> DE[DevError] All Milo errors extend MiloError(code, message): Exception Subsystem Code prefix InputError Key reader, raw mode, escape sequences M-INP-* StateError Store, dispatch, reducers, sagas M-STA-* FormError Form fields, validation, navigation M-FRM-* AppError Event loop, rendering, lifecycle M-APP-* FlowError Flow screens, transitions, navigation M-FLW-* DevError Dev server, file watching, hot reload M-DEV-* Error codes The ErrorCode enum defines all known error codes: Input State Form App / Flow / Dev Code Name Description M-INP-001 INPUT_RAW_MODE Failed to enter raw terminal mode M-INP-002 INPUT_READ Error reading from stdin M-INP-003 INPUT_SEQUENCE Unrecognized escape sequence Code Name Description M-STA-001 STATE_DISPATCH Error during action dispatch M-STA-002 STATE_REDUCER Reducer raised an exception M-STA-003 STATE_SAGA Saga execution failed Code Name Description M-FRM-001 FORM_VALIDATION Field validation error M-FRM-002 FORM_FIELD Invalid field configuration Code Name Description M-APP-001 APP_RENDER Template rendering error M-APP-002 APP_LIFECYCLE Event loop lifecycle error M-FLW-001 FLOW_NAVIGATE Invalid screen navigation M-FLW-002 FLOW_TRANSITION No transition defined M-DEV-001 DEV_WATCH File watching error Catching errors from milo import MiloError, StateError try: store.dispatch(action) except StateError as e: print(f"[{e.code}] {e.message}") except MiloError as e: print(f"Milo error: {e}") Tip Tip Catch specific subclasses (StateError, FormError) when you can handle them. Catch MiloError as a fallback for unexpected errors.

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Metadata:
- Author: lbliii
- Word Count: 229
- Reading Time: 1 minutes