# RuntimeError: Form data requires "python-multipart" to be installed.

- **ID:** `python/fastapi-form-data-requires-python-multipart`
- **Domain:** python
- **Category:** install_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Using Form(...) or File(...) without the python-multipart package installed.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 0.100.x | active | — | — |
| 0.110.x | active | — | — |

## Workarounds

1. **** (99% success)
   ```
   pip install python-multipart
   ```
2. **** (97% success)
   ```
   echo 'python-multipart>=0.0.9' >> requirements.txt
   ```

## Dead Ends

- **** — If the client sends form-encoded data, FastAPI still needs multipart to parse it. (70% fail)
- **** — Wrong package name; FastAPI imports python_multipart. (90% fail)