I have an interesting situation:
We were running GP 2015 through a citrix app and had shut it down as well as removed the database. However, we had a situation arise in which we needed access to GP.
We were able to restore the GP server so that we can run the app. We were also able to restore the database but on a separate server from the original.
I was able to access the databases through the Database Maintenance Utility, however I am unable to login with any account. All I receive is the no descriptive error below:

After googling for many hours I have not found any other instances of this error. Has anyone else run into this login error? Or is there another was to "re-sync" logins or any such thing?
Any help or advice is appreciated.
Thank you!
Lucas