# ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts. <package> is installed but <dependency> is missing.

- **ID:** `pip/pip-requires-virtualenv`
- **Domain:** pip
- **Category:** install_error
- **Error Code:** `ERROR`
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Pip's resolver does not check the full set of installed packages when resolving dependencies, leading to conflicts when a package requires a dependency that is not installed or is an incompatible version.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| pip 21.3 | active | — | — |
| pip 22.0 | active | — | — |
| pip 23.0 | active | — | — |

## Workarounds

1. **Create a fresh virtual environment and install packages with pinned versions: `python -m venv venv && source venv/bin/activate && pip install -r requirements.txt`** (85% success)
   ```
   Create a fresh virtual environment and install packages with pinned versions: `python -m venv venv && source venv/bin/activate && pip install -r requirements.txt`
   ```
2. **Use `pip check` to identify and manually fix missing or conflicting dependencies, then install missing packages: `pip install <missing-dependency>==<compatible-version>`** (75% success)
   ```
   Use `pip check` to identify and manually fix missing or conflicting dependencies, then install missing packages: `pip install <missing-dependency>==<compatible-version>`
   ```

## Dead Ends

- **** — The resolver behavior is inherent to pip's design and not fixed by version upgrades alone. (60% fail)
- **** — This can break environment consistency and may reintroduce the same conflicts if requirements are not pinned. (50% fail)