When trying to add a user as a Server Admin to Analysis Services, you may encounter one of the following errors:
The following system error occurred: The trust relationship between the primary domain and the trusted domain failed.
The following system error occurred: No mapping between account names and security IDs was done.
When you see this, you want to look for an entry in the Admin list that looks like a SID (Security Identifier) instead of the actual account name. For example:
This emails that the account that was listed as a Server Admin was probably deleted, or if you were in a Trusted Domain scenario, the Trust may have been broken preventing the ability to resolve the SID to the account name.
If you see this, and then add a new user, when you hit on the OK button on the bottom, you will see one of the two errors above. The first error could come up if you are in that Trust Domain Scenario and the user was from a different domain. The second error may come up if it was just a user in the same Domain as the SSAS Service.
To get around this issue, remove the SID account and then you should be able to add the new Admin account normally.