# numpy.core._exceptions._UFuncNoLoopError: ufunc 'add' did not contain a loop with signature matching types (dtype('<U3'), dtype('<U3')) -> None

- **ID:** `python/numpy-ufunc-type-error`
- **Domain:** python
- **Category:** type_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Attempting arithmetic on string arrays; NumPy has no add loop for Unicode dtype.

## Version Compatibility

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

## Workarounds

1. **** (95% success)
   ```
   arr = arr.astype(float) before arithmetic
   ```
2. **** (90% success)
   ```
   Use pd.to_numeric(arr, errors='coerce') to convert
   ```

## Dead Ends

- **** — Still fails for '+' on strings (80% fail)
- **** — Same ufunc error (85% fail)