Creds do not authenticate against any registered id provider
1. Let say you have created new user account in internal identity provider and you would use this user id for gateway health check
2. If the authentication of this user is failing the reason could be the password policy.
1. Login to policy manger
2. Go to Tasks -> Manage Account policies -> Manage password policy
3. Uncheck Force password change for new user and reset
or
4. Login to policy manager using this new user and change the password and then use this account for authentication