When I click "Add" in the Privileges window, instead of receiving the list of users, I receive the error below. If I click "OK", I can type in a user. I have been unable to find any help online.
What version of ArcGIS Desktop and SQL Server are you working with?
I apologize for not including that initially. I am using ArcGIS Desktop 10.7 and SQL Server 2012. This has been an ongoing problem through 10.6 and 10.6.1, all with SQL Server 2012.
Thank you for sending that information.
Just to confirm. Is that a SQL Server 2012 with no Service Pack? If yes, this may be a version compatibility issue. I've seen this behavior before and it is solved by upgrading the DBMS to a supported version.
If you are using an ArcGIS Desktop 10.7 client, the earliest version of SQL Server you can connect to is Microsoft SQL Server 2014 SP3 (64-bit). See all SQL Server supported versions for ArcGIS Desktop 10.7 here.
If you are using an ArcGIS Desktop 10.6.x client, the earliest version of SQL Server you can connect to is Microsoft SQL Server 2012 SP3 (64-bit). See all SQL Server supported versions for ArcGIS Desktop 10.6.x here.