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HTTP 401 Unauthorized

Authentication is missing or invalid for this request.

4xx · Client error✗ not retryable — fix the request instead

In AI APIs specifically

Anthropic expects the x-api-key header; OpenAI expects Authorization: Bearer. Mixing the two conventions is the classic cause. Revoked or rotated keys also land here.

Fix checklist

  • Verify the correct auth header for the provider.
  • Check the key is set in the environment the process actually reads.
  • Confirm the key wasn't rotated or revoked in the console.
  • Watch for whitespace/newlines accidentally included in the key.

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..

402 Payment Required

The request requires payment — billing is not set up or a balance is exhausted..

403 Forbidden

The server understood the request but refuses to authorize it — valid credentials, insufficient permission..

404 Not Found

The requested resource does not exist at this URL..

← All HTTP status codes