# jinja2.exceptions.TemplateNotFound: index.html

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

## Root Cause

Flask blueprint's template folder not set or template file not in expected directory.

## Version Compatibility

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

## Workarounds

1. **** (95% success)
   ```
   Set template_folder in Blueprint: bp = Blueprint('bp', __name__, template_folder='templates')
# Ensure templates/index.html exists in blueprint package
   ```
2. **** (85% success)
   ```
   Use app.add_template_folder to add additional template directories
   ```

## Dead Ends

- **** — Blueprint defaults to app's template folder unless overridden. (60% fail)
- **** — render_template expects relative path to template folder. (80% fail)