# werkzeug.exceptions.RequestEntityTooLarge: 413 Request Entity Too Large: The data value transmitted exceeds the capacity limit.

- **ID:** `python/flask-max-content-length-413`
- **Domain:** python
- **Category:** config_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

MAX_CONTENT_LENGTH set lower than the upload size, or reverse proxy (nginx client_max_body_size) rejects first.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 2.x | active | — | — |
| 3.x | active | — | — |

## Workarounds

1. **** (92% success)
   ```
   app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 * 1024  # 16 MB
   ```
2. **** (90% success)
   ```
   In nginx: client_max_body_size 16m;  # align with app config
   ```

## Dead Ends

- **** — Removes DoS protection; still capped by proxy. (70% fail)
- **** — Body was never read; handler has no data. (85% fail)