# ERROR: Cannot install foo==1.0 and bar==2.0 because these package versions have conflicting dependencies. The conflict is caused by: foo 1.0 depends on baz<2; bar 2.0 depends on baz>=2

- **ID:** `python/pip-resolver-conflict-incompatible`
- **Domain:** python
- **Category:** install_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

The new pip resolver (pip >= 20.3) performs full backtracking and detects that no single set of versions satisfies all constraints. Two dependencies require mutually exclusive ranges of a shared package.

## Version Compatibility

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

## Workarounds

1. **** (85% success)
   ```
   pip install 'foo<1.0' 'bar>=2'  # try ranges
# or use pip-tools to resolve:
pip install pip-tools
pip-compile requirements.in
   ```
2. **** (75% success)
   ```
   python -m venv venv_foo && venv_foo/bin/pip install foo
python -m venv venv_bar && venv_bar/bin/pip install bar
# call via subprocess from a coordinating process
   ```

## Dead Ends

- **** — The legacy resolver just picks one arbitrarily and installs an inconsistent environment that breaks at runtime with ImportError or AttributeError. (85% fail)
- **** — Skips dependency installation entirely, leaving baz missing or at the wrong version so imports fail. (80% fail)