Assume that you use SQL Server 2017, you may notice that rebuilding system databases will remove login for SQL Server Customer Experience Improvement Program (CEIP). In addition, a lot of SQL error 18456 may be generated when you try to run dynamic management view (DMV) queries on the SQL Server instance after the rebuilding.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
This issue is fixed in the following cumulative update for SQL Server:
About cumulative updates for SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
Learn about the terminology that Microsoft uses to describe software updates.