(holding Shift during startup) can clear system conflicts and allow the export to complete. Apple Support Community
Apple does not provide direct public download links for specific older versions like 10.1.12. The Mac App Store always serves the latest compatible version for your macOS. imovie 10.1.12 download
Users of iMovie 10.1.12 have documented several technical limitations that may require manual workarounds: Resolution Locking : The resolution of an entire project is determined by the very first clip (holding Shift during startup) can clear system conflicts
Key features of iMovie 10.1.12 include: