When you migrate to a new Mac, as I did last December, it is easy to assume that apps purchased from the App Store, like OS X Server and Xcode, get migrated too. They appear on your new Mac, and appear to work. Server continues to provide its services, and Xcode will edit and compile code, just as they did on your previous Mac.

Only now – six months after I migrated to this new iMac – has it become clear that those copies of the Server and Xcode apps are shadows of their former selves, orphaned from updates, and stunted in their behaviour.

It all started when I received notification of the recent Xcode 7.3.1 update, from Apple’s security mailing list. I checked for App Store updates, but several days after I knew that the update had been released, I had still not been offered it. Checking through my Purchased list in the App Store app revealed that two products were being offered for INSTALL, despite being installed: OS X Server and Xcode.

So the App Store thought that they weren’t installed on this Mac. I ran them both, and they still seemed to work fine. Neither app coughed or farted at me, and seemed to run just as they had on my previous iMac. Neither considered that they needed to install anything afresh, Xcode’s docs were all up to date – there was nothing in the apps to indicate that they were but shadows dissociated from their reality.

I then accepted the App Store’s generous invitation to install both.

Thankfully Xcode did not decide that it needed a new documentation set, and its command-line tools appeared to be good still.

I am not sure what went wrong with my initial migration, which used the Time Machine backup of my old iMac as its source. There did not appear to have been any errors or warnings that either OS X Server or Xcode had not be installed correctly. Neither can I find any warnings by Apple – or comments from anyone else – that this can happen.

Is this just a strange local quirk, or a general problem with migrating OS X Server and Xcode to a new Mac? And why should it be so – is it just a bug between the App Store and Migration Manager?

So if you have migrated either app to a new Mac, you might like to check that they are not shadow installations. The App Store app should tell you clearly.