# ERROR: 403 Client Error: Forbidden for url: https://private-pypi.example.com/simple/mypackage/

- **ID:** `python/pip-extra-index-url-invalid`
- **Domain:** python
- **Category:** auth_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

The extra index URL requires authentication or is not accessible from the current network.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.8 | active | — | — |
| 3.9 | active | — | — |
| 3.10 | active | — | — |
| 3.11 | active | — | — |
| 3.12 | active | — | — |

## Workarounds

1. **Provide credentials in the index URL** (85% success)
   ```
   pip install --extra-index-url https://username:password@private-pypi.example.com/simple mypackage
   ```
2. **Use a .netrc file for authentication** (90% success)
   ```
   echo 'machine private-pypi.example.com login username password password' >> ~/.netrc && chmod 600 ~/.netrc
   ```

## Dead Ends

- **Using --trusted-host without credentials** — Trusted-host only bypasses SSL verification, not authentication. (80% fail)
- **Adding the URL to pip.conf without credentials** — pip still needs authentication for private repositories. (70% fail)