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AMZScratchpad

MissingKeyId (UnauthorizedException): Amazon Creators API error

HTTP 401UnauthorizedExceptionAuthentication (401)Documented by Amazon

What it means

The token was not issued by Amazon’s official token endpoint: its key ID (kid) is missing.

Message returned by the API: The authentication token is missing the required key identifier.

Typical causes

  • A self-made or mocked token.
  • A token from a proxy that rewrites the Authorization header.

How to fix it

  1. Use the token exactly as returned by the official token endpoint.
  2. Check proxies and middleware that touch the Authorization header.

Not sure which part fails? Run Test credentials in the Scratchpad. It checks the token, the API access and the partner tag separately.

Example response

{
  "type": "UnauthorizedException",
  "message": "The authentication token is missing the required key identifier.",
  "reason": "MissingKeyId"
}

Related errors

  • InvalidToken: The access token in the Authorization header is broken, incomplete or in the wrong format.