Log file messages:
(Single Sign-On) Negotiation complete; authentication granted for user "...".
(Single Sign-On) Failed authentication because user "..." could not be found in Active Directory.
Cause
Single sign-on authentication was attempted and succeeded, but the user does not exist in the configured Windows domain.
Resolution
Ensure that the user account used to log into the client machine is a part of the Windows domain that FME Server is configured to use.
For example, if FME Server is configured to use Active Directory for 'Domain1', clients logged in using a 'Domain2' user account will not be able to authenticate with FME Server.