This has been going on for as long as I've had Windows 10 and I continue to be unable to find a solution. For a while, I was finding other people on various forums with the same problem - some of them were talking about a COM surrogate error - but never found anything useful.

Inside the Photos app, if I trim a video or edit photos, I often get an error when I try to save the new file. It says "Try saving a copy instead. This file is locked by another app right now."

I've taken ownership of everything, I've tried saving copies and then editing the copy, I've tried saving to different locations...nothing ever works.