# ERROR: Command errored out with exit status 128: git clone --filter=blob:none --quiet https://github.com/user/private-repo.git ... (fatal: Authentication failed for 'https://github.com/user/private-repo.git/')

- **ID:** `python/pip-vcs-url-authentication-failed`
- **Domain:** python
- **Category:** auth_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Pip cannot authenticate to a private VCS repository; missing credentials or SSH keys.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.10 | active | — | — |

## Workarounds

1. **Use SSH URL with SSH keys configured** (90% success)
   ```
   pip install git+ssh://git@github.com/user/private-repo.git
   ```
2. **Use personal access token in URL** (85% success)
   ```
   pip install git+https://<token>@github.com/user/private-repo.git
   ```

## Dead Ends

- **Using --no-cache-dir** — Cache is not the issue; authentication is required. (90% fail)
- **Removing the package from requirements** — Package is needed; removal breaks functionality. (60% fail)