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AMZScratchpad

invalid_client: Amazon Creators API error

HTTP 401Token endpointObserved in live responses

What it means

Amazon’s token endpoint rejected your Credential ID or Secret, so no access token was issued.

Message returned by the API: Client authentication failed

Typical causes

  • Typo or missing characters in the Credential ID or Secret.
  • Wrong Version selected, so the request goes to the token endpoint of another region.
  • The credential was deleted in Associates Central.
  • You used old PA-API 5 Access/Secret Keys. They do not work with the Creators API.

How to fix it

  1. Import the CSV you downloaded when creating the credential, or copy the values again.
  2. Select the Version from that CSV (3.1 NA, 3.2 EU, 3.3 FE).
  3. If the secret is lost, create a new credential. The secret is only shown once.

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

{
  "error_description": "Client authentication failed",
  "error": "invalid_client"
}

Note: Response of the Login with Amazon endpoint, observed with made-up credentials. It follows the standard OAuth 2.0 error format.

Related errors

  • AuthorizationFailed: Your login worked, but this credential may not use the API, most often because the credential itself has expired.
  • InvalidIssuer: The token comes from the wrong token endpoint for your credential version.