# 400 Bad Request: API version header required

- **ID:** `api/rest-api-version-header-required`
- **Domain:** api
- **Category:** config_error
- **Verification:** ai_generated
- **Fix Rate:** 92%

## Root Cause

The API endpoint requires a specific version header (e.g., Accept-Version or X-API-Version) that was not included in the request.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| REST API v1.0 | active | — | — |
| Stripe API v2023-10 | active | — | — |
| GitHub API v3 | active | — | — |

## Workarounds

1. **Add the required version header to every request.** (95% success)
   ```
   Add the required version header to every request.
   ```
2. **Use an API client configuration that automatically includes the version header.** (90% success)
   ```
   Use an API client configuration that automatically includes the version header.
   ```

## Dead Ends

- **** — The API specifically checks the header; query parameters are ignored for versioning. (80% fail)
- **** — Some APIs require explicit versioning; no default is assumed. (90% fail)
- **** — The version check is often middleware-level and applies to all methods. (95% fail)