API error · HTTP 401

`invalid_client`

Client authentication failed

HTTP status	401 Unauthorized
`code`	`invalid_client`
`title`	Client authentication failed
Retry?	No

What it means

The token endpoint could not authenticate the client: the client ID or secret is wrong, the credential was revoked, or the Authorization header is malformed. The token endpoint answers this as an OAuth error body ("error": "invalid_client"), not as problem+json (§4.1).

What to do

Do not retry in a loop. Check that the client ID and secret come from the right environment (sandbox and production credentials are separate) and the platform's secret store. If they are correct, the credential may have been revoked or rotated: alert the integration owner (§4.4).

Example response

Returned by the token endpoint (POST /v1/oauth/token) as an OAuth 2.0 error (RFC 6749 §5.2), not as problem+json:

HTTP

HTTP/1.1 401 Unauthorized
Content-Type: application/json

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

All error codes · Error catalogue in the integration guide (§15) · Error handling and retries (§12.4)