We attempted to upgrade SQL 2008 to 2008 R2. It passed the checks with flying colors. But midway through the installation we got the dreaded "No mapping between account names and Security IDs was done" error.
After much Googling, we believe we have fixed the SID issue (we found an invalid SID in the registry for the installation SQL Group and changed it to the correct SID). The first installation attempt finished but did not fully upgrade the 2008 instance, only some of the shared components.
Now we cannot finish running the upgrade. Partway into the installation wizard it shows a screen where it lets you check/uncheck components to be upgraded. These are all pre-checked and cannot be unchecked. When we click "next" it says there is nothing to be upgraded and stops on a validation error. We're pretty much stuck right there. The instance is still SQL 2008 (10.0.2531) not R2 (10.50.1600). For giggles, we tried the "Repair" wizard, it ran to completion but did essentially nothing.
I think what is happening is the installer thinks the instance has already been upgraded, when in reality it has not been fully upgraded to R2.
Short of uninstall/reinstall or installing a named instance (the boss hates named instances with a passion and only allows default instances) is there anything we can do to complete the upgrade to R2?