# ValueError: Unknown path converter 'int'

- **ID:** `python/starlette-route-param-converter`
- **Domain:** python
- **Category:** config_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Using a path converter that Starlette doesn't support, such as int without proper syntax.

## Version Compatibility

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

## Workarounds

1. **** (100% success)
   ```
   Use the correct syntax: @app.route('/items/{item_id:int}')
   ```
2. **** (95% success)
   ```
   In FastAPI, use type annotation: @app.get('/items/{item_id}') with item_id: int
   ```

## Dead Ends

- **** — Starlette uses {item_id:int} syntax, but it must be exactly that; if you use {item_id} with a type annotation, it's different. (70% fail)
- **** — The converter is built-in; no import needed. (30% fail)