I'm getting this error when opening an iMovie library that I copied from another machine. I copied it and overwrote ~/Movies/iMovie Library.imovielibrary
.
"iMovie Library” could not be opened. You don’t have permission to save the file “FFLibraryUpgradeLock” in the folder “iMovie Library
I have made sure that iMovie has "File access". I even granted iMovie full disk access.
Best Answer
I ended up just creating a dummy file called
FFLibraryUpgradeLock
inside the lib directory$ touch ~/Movies/iMovie Library.imovielibrary/FFLibraryUpgradeLock
and then started iMovie. Everything works fine now and I can see all the projects in the old library.