unable to export in imovie using high sierra
I am unable to export in iMovie. I'm using macOS High Sierra 10.13.6. My iMac is 4K, 21.5 inch (2017) 3.4Ghz Intel Core i5.
I am unable to export to file, or youtube or anything. It was working fine last time I used it which was about a month ago I think. I'm. not saving to an external drive.
I've looked up some suggestions, I've deleted the preferences in iMovie, I've restarted my computer, I've created a new library, but I keep coming up with the same error, see attached, I'd love any advice.
Thanks Lisa
iMac 21.5", macOS 10.13