GRC 5.3 - Login credentials not valid to request access

Hi,

We are currently using Access Enforcer 5.3.

When I try to request access through AE, On clicking "Request Access", on the home screen, and on entering user id, I am facing the error "User credentials not valid". But my id exists in the SAP system, Which is the user data source.

I have logged in successfully in the past and no recent changes to my user master record.

Could you please tell me what is causing this problem?

Thanks in advance,

Aravindan