Mac Mini Server in weird state after SSW upgrade

I’ve got an old Mac Mini Server (2009, MacMini3,1) that has been happily running 10.6.8 Server for the last 8 years. I had to ‘upgrade’ it to Mavericks for various reasons and now it’s all weird.

It’s partially working - About this Mac says it’s running 10.9.5 - but the UI still looks like it’s 10.6.8 and various things don’t work.

I can’t, for example, get the App Store to do anything. It launches, but everything is greyed out and it’s basically completely unresponsive even though the menu items that should be selectable are. They just do nothing and none of the tabs can be selected. It also still has both Software Update and App Store entries in the Apple Menu. And the 10.6.8 version of Safari, among many other strange things.

I’ve tried restarting it a few times. I’m guessing I will need to reinstall 10.9.5, but I can’t download it again directly at the moment and I would still prefer not to just nuke the startup disk from low orbit if possible.

Any thoughts?

Your mileage may vary, but I had a failed update about six months ago and the machine would no longer boot (power outage of the whole suburb during the update, can you believe it?)

I booted from a startup external disk and installed over the top and it’s been fine ever since. BUT I had a Time Machine backup from about an hour before, so I wasn’t too worried about doing it as I had a fallback plan.

Well, it must have just needed a rest because I got the App Store to work ok this morning and, after applying all the updates and checking it with various utilities, it all seems to be ok. The UI still looks odd, but I must have just forgotten what changed when.

What a nightmare! I always used to dread this when I was doing firmware updates and stuff. I’ve got a whole house UPS (battery storage) now though, so don’t have to think about that anymore.