# ValueError: 'viridis' is not a valid colormap name. Valid names are: ['Accent', 'Accent_r', 'Blues', ...]

- **ID:** `python/matplotlib-cmap-name-error`
- **Domain:** python
- **Category:** config_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Using a typo in colormap name (e.g., 'viridis' instead of 'viridis'? Actually 'viridis' is correct; if user types 'viridiss' or 'virid' it fails). The error occurs when the string does not match any registered colormap.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.8 | active | — | — |
| 3.9 | active | — | — |

## Workarounds

1. **Use the correct spelling from the list of valid colormaps** (95% success)
   ```
   plt.imshow(data, cmap='viridis')
   ```
2. **List all available colormaps to find the correct one** (90% success)
   ```
   from matplotlib import cm; print([m for m in cm._cmap_registry.keys()])
   ```

## Dead Ends

- **Assuming case insensitivity and trying 'Viridis'** — Colormap names are case-sensitive; 'Viridis' is not valid, only 'viridis' works. (80% fail)
- **Using a numeric index like 0 for the first colormap** — Colormaps are accessed by name, not numeric index. (90% fail)