Why won't iMovie and GarageBand work after upgrade to OS 12.7.1

Well, one needs to put iMovie in the trash before doing a redownload of the same version. Possibly when doing an update to a later version it would not be necessary to put it in the trash first. You may be right there.

I think in the situation of the OP we are dealing with 32 bit apps being incompatible with 64 bit operating system. So I am not sure that you can do the usual update method. In any event, since the update procedure was not working for the OP, then it doesn't hurt to put iMovie in the trash and re-try the procedure.

Open the AppStore, sign in and click on your name at the bottom left.

All the apps you own will be shown on the right . . . if you have a lot you may have to scroll up or down to find iMovie.

iMovie should have an Update button beside it. Mine hasn't because I already have the latest version.

I can't understand what is causing the problem.

Open the AppStore and type "iMovie" into the search box top left.

Click on the magnifying glass icon or press the Enter/Return key and iMovie should appear as in this screenshot.

The screen shot of your Account shows you have 5 Apps to adopt two of which are iMovie and Garage Band.

The iMovie and Garage Band shown further down the Account page might be from downloads from a previous Mac and then migrated over to your newer Mac???

Anyway it looks as though you have to accept the Apps before you can update them.

You might need to trash your current versions of iMovie and Garage Band first to avoid any confusion.

Before the updating procedure for iMovie will work you first need to drag your iMovie application icon from the Applications folder into the trash. Don't empty the trash until you get a successful update.

-- Rich

That's worth knowing but I have never had to do that having left iMovie in situ with the updated version overwriting it.

I only updated a few days ago and was miffed when it got deleted as I thought I had not got a copy of the old one . . . luckily I had on another drive.

The applications aren't opening because they are 32 bit applications, whereas Apple changed to 64 bit after the Mojave operating system. A 32 bit application is not compatible with a 64 bit operating system. That's why you need to update the applications.

-- Rich