# fastapi.exceptions.RequestValidationError: path -> id
  value is not a valid uuid (type=type_error.uuid)

- **ID:** `python/fastapi-path-param-422-uuid`
- **Domain:** python
- **Category:** data_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

The path parameter is declared as UUID but the URL segment is not a valid UUID string.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.x | active | — | — |

## Workarounds

1. **** (90% success)
   ```
   @app.get('/items/{item_id}')
def get(item_id: str):
    try: uid = UUID(item_id)
    except ValueError: raise HTTPException(400)
   ```
2. **** (88% success)
   ```
   from fastapi import Path
def get(item_id: UUID = Path(...)): ...
   ```

## Dead Ends

- **** — Still fails if the regex matches but the value is not a UUID. (75% fail)
- **** — Validation runs before the handler; except never triggers. (90% fail)