# ERROR: pip._vendor.packaging.requirements.InvalidRequirement: Expected ',' or end of string, got ';' in requirement 'numpy; python_version<"3.8"'

- **ID:** `python/pip-unsupported-format-version`
- **Domain:** python
- **Category:** data_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

The requirement string uses a semicolon for environment markers, but the syntax is incorrect or the packaging version is too old.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.7 | active | — | — |
| 3.8 | active | — | — |

## Workarounds

1. **Use proper syntax with environment markers** (95% success)
   ```
   Write: 'numpy; python_version < "3.8"' (note space after semicolon and proper quoting).
   ```
2. **Upgrade packaging to support modern syntax** (90% success)
   ```
   Run: pip install --upgrade packaging
   ```

## Dead Ends

- **Removing the semicolon and marker entirely** — Loses conditional installation logic. (70% fail)
- **Using double quotes inside the marker** — Syntax remains invalid; markers require proper quoting. (80% fail)