Facing 401 Authentication-Errors

We are facing an Invalid Authentication Certificate error while reporting invoices in the Simulation environment.

The response we are receiving is:

{{“validationResults”:{“infoMessages”:,“warningMessages”:,“errorMessages”:[{“type”:“ERROR”,“code”:“Authentication-Errors”,“category”:“Invalid-Authentication-Certificate”,“message”:“”,“status”:“ERROR”}],“status”:“ERROR”},“clearanceStatus”:“NOT_CLEARED”,“clearedInvoice”:null}}
The invoice is therefore not being cleared, and the response shows clearanceStatus: NOT_CLEARED.

Could you please check and advise us on the required action to resolve this issue?
@idaoud @Ankit.K.Tiwari

Thank you.