# ERROR: File 'pyproject.toml' does not define a 'build-system.requires' table.

- **ID:** `python/setuptools-pyproject-missing-build-system`
- **Domain:** python
- **Category:** config_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

A pyproject.toml exists but lacks a [build-system] section, so pip cannot determine the build backend. This often happens when a tool writes a partial pyproject.toml.

## Version Compatibility

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

## Workarounds

1. **** (90% success)
   ```
   [build-system]
requires = ["setuptools>=61", "wheel"]
build-backend = "setuptools.build_meta"
   ```
2. **** (75% success)
   ```
   pip install build
python -m build --sdist  # validates pyproject.toml
   ```

## Dead Ends

- **** — Disabling isolation doesn't supply the missing build-system table; pip still refuses to proceed. (85% fail)
- **** — Removing the file forces legacy setup.py behavior, which may not exist for a PEP 517-only project. (60% fail)