| Issue | Solution | |-------|-----------| | | This is a quarantine flag. Run xattr -d com.apple.quarantine /Applications/iMovie.app in Terminal. | | Installation requires macOS 11.0 or later | You have the wrong version. 10.3.3 works on 10.14.6–11.x. Double-check your OS. | | Crashes on import of HEVC/iPhone footage | Install legacy video codecs from Apple’s "Pro Video Formats" package (version 2.2.1). | | iMovie Library won't open | Use "File → Open Library → New" to create a fresh library. Then use "File → Import" to bring in old events. |