Cannot find SQL instance when applying patch


One customer had a SQL2016 SP1 instance. We can login this instance without any issue. But when we tried to apply SQL2016 SP2 in this server. We cannot find SQL instance in below panel. Only ‘Shared Features’ are listed.

 

I decompiled SQL setup dlls. It seems that SQL setup should check below registry key to Enumerate SQL Server features.

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionUnistall

 

We found below key was missing in customer’s environment. We tried to remove below key in my testing environment. We can reproduce the same issue.

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionUninstallMicrosoft SQL Server 13

However, after adding back above key. SQL instance