How to fix 'iMovie Library.imovielibrary' could not be opened due to newer version?

Hi,

When you open an iMovie library in a newer version of iMovie than the version that created the library, then the library will update (be created in a newer version) and can no longer be opened in the older iMovie app version that originally created it. You would need to open it in the newer iMovie app version or a later version than that. If you update your iMovie app to current version you should be able to open the library.

Try updating first, and if that doesn't work you might be able to open an older saved version of the library that is contained in the iMovie Backups folder. To get to the iMovie Backups folder, follow this file path from the Finder menu:

Go/Home/Library/Containers/iMovie/Data/Library/Caches/iMovieBackups

When you get there you will see a list of previous backups of your iMovie library. Click on one dated just before your issue started.  iMovie will open in that library.   Navigate to your projects browser (where your projects are displayed as icons) and see if your projects are intact.

If still no luck, you could open the older version of the library by using your Time Machine backup to recover the older version from an earlier point in time.

-- Rich