I awoke this morning to flurries of happy activity in my Twitter feed: Reeder for Mac was finally out of beta, and available for £5.99/$9.99 on the Mac App Store. Reeder is a fantastic RSS reader that I totally fell for on the iPad, and I’ve used the Mac version since the earliest beta. A couple of iterations in, I binned NetNewsWire, because even a feature-incomplete Reeder suited me better.
As a Mac journo, I get a lot of free software, but there are a few cases—notably, indie apps that I use daily—where I transition from ‘free stuff’ to paying for the product myself. For me, Reeder was in insta-buy territory, but, helpfully, the Mac App Store wouldn’t let me pay for a copy. Instead, it told me:
A newer version of this app is already installed on this computer
Well, thanks for that, Mac App Store. I trashed the Reeder beta, went through my ~/Library folder to remove Application Support and Preferences files. Still no dice. I then trashed support files in a copy of my old computer’s home folder that’s lurking on my new Mac. Still, the Mac App Store stubbornly claimed a ‘newer’ version of the app was installed, even though Mac OS X’s System Profiler disagreed that any version of Reeder existed on the system.
Then it struck me: I have a back-up hard-drive attached to the Mac, which is a clone taken by SuperDuper!, and, sure enough, the Mac App Store seemingly cannot tell the difference between the active volume and the back-up—at least in this case. And so if the Mac App Store tells you that you can’t install an app and you’re using cloning software, try temporarily unmounting the clone and see if that helps.
UPDATE: Alex Chan says in the comments that this problem extends to additional hard-drive partitions with installed apps.