A lot of users have been reporting recent problems with App Store updates, particularly in macOS Mojave. These aren’t confined to older versions of macOS, but can affect Big Sur too. When it happened to me a couple of days ago, I browsed through the log in an attempt to discover what the problem was. This article describes the outcome.

For a few weeks now, App Store updates have been irritating to say the least. I run a Content Caching Server here, on the same Mac which does most of the updating. Although that doesn’t help on the first attempt to update an app from the App Store, as it still has to be downloaded, subsequent attempts should be significantly faster.

The pattern is well-established: the progress circle steadily completes until it reaches around 11 o’clock, then it stops, moves forward a bit more, and only completes the final stretch after many minutes, sometimes as long as 15-20. This appears to coincide with the phase in which that update is fully installed and authorised, suggesting that it might have something to do with certificates and purchase authorisation.

When an update to OmniGraffle repeatedly failed right at the end on many occasions, I looked through the log for the moment that error occurred. It was of little help: what had apparently gone wrong was that a non-existent path was accessed during the update process. As there was insufficient information in the log, it forced me to fall back on the traditional treatment: delete that app altogether, and try downloading it again.

With the App Store, that’s the least disruptive of a small number of solutions, ranging from that up to signing out of the Store and iCloud altogether, and signing back in, or killing processes which may not even be involved in the error.

It was when I came to delete the app that I realised why this particular update was failing every time: I had two copies in my Applications folder, one at the top level, the other inside another folder. Once both had been removed, the App Store was quite happy to deliver a complete fresh copy, which now runs perfectly.

I’m not suggesting that all your App Store problems can be solved as simply, but sometimes traditional remedies do work very well indeed.