# findfont: Font family 'Arial' not found.

- **ID:** `python/matplotlib-findfont-cache-stale`
- **Domain:** python
- **Category:** config_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

The requested font is not installed on the system, or matplotlib's font cache is stale after installing a new font.

## Version Compatibility

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

## Workarounds

1. **** (90% success)
   ```
   sudo apt-get install -y fonts-liberation
rm -rf ~/.cache/matplotlib
python -c "import matplotlib.font_manager as fm; fm._load_fontmanager(try_read_cache=False)"
   ```
2. **** (95% success)
   ```
   import matplotlib.pyplot as plt
plt.rcParams['font.family'] = 'DejaVu Sans'  # shipped with matplotlib
   ```

## Dead Ends

- **** — The font file is genuinely absent; naming it does not create it. (93% fail)
- **** — Upgrading matplotlib does not install OS-level font packages. (88% fail)