iMovie Export fail

What steps did you use to export and what happened when you tried? Any error message? Does the inability to export happen with all projects? Have you updated your iMovie app to current version 10.1.14? If so, have you tried redownloading iMovie?

You can try some of these diagnostic procedures to see if you can cure the problem:

Updating iMovie

To update/redownload iMovie 10, drag your iMovie 10 app from the Applications

folder into the trash, but do not empty the trash. Sign in to the app

store and open your purchases folder by clicking on your name at the bottom of

the app store side bar. You will see your purchases displayed, including iMovie

10. Redownload/update iMovie from there. If not successful, drag your present

iMovie app out of the trash and return it to the Applications folder.

Deleting Preferences

Try opening iMovie while holding down the Option and Command keys and selecting to

delete preferences in the box that appears. iMovie will open in a new library.

Reopen your old library to get back to your projects. Now see if the artifacts

are gone.

New Project

Another thing you can try is to copy your media into a newly created project and see if

that cures the problem. To do that, do an Edit/Select All, Edit/Copy, of the

media in your project and then Edit/Paste it into the newly created project.

Safe Mode

You could also try booting up in Safe Mode (see Finder menu for instructions) and,

after everything loads, immediately shut down and reboot in normal mode. Then

see if iMovie works properly.

Resetting the System Management

Controller

Try resetting the System Management Controller:

https://support.apple.com/en-us/HT201295

-- Rich

I have the same issue. I tried doing it in safe mode too but it does not work. I have reported this issue to the Apple support team member and they have created an engineering ticket for this issue. I am still waiting on either OS update or imovie update to fix this issue. Hope it comes soon !! Fingers crossed.

They suggested me to erase the hard disk and reinstall the OS. But , after doing that as well I am facing same issue. . Now they are telling that it can be a hardware issue related to GPU but this was never a problem before the OS update Catalina 10.15.5.

Let me know if problem is solved or you have any input on this.