Integration Error

Hi Team,

I have one Integration with POST request have used OAuth 2.0 Client Credential Grants.

Initially was fine but now i am sporadically getting 403 errors.

When i check log below is the snap

com.appiancorp.connectedsystems.http.oauth.HttpOAuthTokenRetriever - Error while retrieving token: request_error attempting to pass Authentication in body
2023-12-20 22:16:23,379 [Appian Work Item - ### - WorkID ### - execution00 - process ### - model ### : UnattendedJavaActivityRequest] ERROR com.appiancorp.connectedsystems.http.execution.AppianHttpRequestExecutor - ConnectorRuntimeException [title=You are not permitted to perform the requested operation, The external system understood the request but refused to authorize it]

I can confirm here, It is not Credential/Privilege issue. integration not even hitting external system.

Please advise if anyone has faced the same.