On SCCM 2012 R2 with WSUS integrated for software update deployments I was unable to open the WSUS console. The WSUS service had stopped and the event log showed event ID 507 Windows Server Update Services, Update Services failed its initialization and stopped. WSUS is configured to use a SQL database and the SQL Server Logs contained multiple errors for Login failed for user ‘DOMAIN\SCCMSERVERNAME$’. Reason: Could not find a login matching the name provided. [CLIENT: <local machine>]
Opening SQL Server Management Studio, I navigated to the SUSDB. Expanding users showed a user for NT AUTHORITY\NETWORK SERVICE.
I next opened Security -> Logins and could not see a login for NT AUTHORITY\NETWORK SERVICE. I added a login for NT AUTHORITY\NETWORK SERVICE and started the WSUS service. this resolved the problem.