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HTTP 405 Method Not Allowed
The URL exists but does not support this HTTP method.
4xx · Client error✗ not retryable — fix the request instead
In AI APIs specifically
Typically a GET against a POST-only inference endpoint, often caused by a redirect that downgraded the method.
Fix checklist
- Use the method documented for the endpoint.
- Check for redirects converting POST to GET.
Spec: RFC reference
Related status codes
400 Bad Request
The server cannot process the request due to a client error — malformed JSON, invalid parameters, or schema violations..
401 UnauthorizedAuthentication is missing or invalid for this request..
402 Payment RequiredThe request requires payment — billing is not set up or a balance is exhausted..
403 ForbiddenThe server understood the request but refuses to authorize it — valid credentials, insufficient permission..