# AssertionError: The name 'auth' is not registered as a blueprint. Did you forget to register it?

- **ID:** `python/flask-blueprint-not-registered`
- **Domain:** python
- **Category:** config_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

A blueprint must be registered with the Flask app before it can be used.

## Version Compatibility

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

## Workarounds

1. **Register the blueprint with the app** (100% success)
   ```
   from myapp.auth import auth_bp
app.register_blueprint(auth_bp)
   ```
2. **Check the blueprint name and register correctly** (95% success)
   ```
   print(auth_bp.name)  # ensure it's 'auth'
app.register_blueprint(auth_bp, url_prefix='/auth')
   ```

## Dead Ends

- **Importing the blueprint but not calling app.register_blueprint** — Registration is required to add routes. (100% fail)
- **Registering with wrong name** — The name must match the blueprint's name attribute. (80% fail)