When you try to log on to SAS Enterprise Guide, instead of logging you on, the system re-displays the prompt for your login credentials. The problem occurs if your domain user account name exceeds the 20-character limit defined in the Microsoft Active Directory directory service.
If your domain is configured to use a SAM-Account-Name attribute in Active Directory, the limitation is 20 characters. A user with a longer user name cannot log on to SAS Enterprise Guide or have their user name authenticated. Instead, they are prompted again for their credentials. This is the same behavior that occurs when an incorrect user name or password is used, because SAS is not able to recognize the user account.
SAS® Metadata user names are limited to the same character length defined in Microsoft Active Directory. As a result, SAS Metadata user names are also limited to 20 characters or less.
Read about the SAM-Account-Name attribute on this Microsoft page.