# PytestUnknownMarkWarning: Unknown pytest.mark.slow - is this a plugin needed to handle it?

- **ID:** `python/pytest-unknown-mark-warning`
- **Domain:** python
- **Category:** config_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

A custom marker like @pytest.mark.slow is used but not registered in pytest configuration. pytest warns and may treat it as a no-op depending on --strict-markers.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 7.x | active | — | — |
| 8.x | active | — | — |

## Workarounds

1. **** (96% success)
   ```
   # pytest.ini
[pytest]
markers =
    slow: marks tests as slow
    integration: marks integration tests
   ```
2. **** (94% success)
   ```
   [tool.pytest.ini_options]
markers = [
  "slow: marks tests as slow",
  "integration: marks integration tests",
]
   ```

## Dead Ends

- **** — Suppresses the warning but the marker still has no registered meaning; with --strict-markers the suite still fails. (70% fail)
- **** — Changes test selection semantics; tests intended to run now get skipped. (80% fail)