I thought I’d share a semi-solution I found to the “Failed To Open” error message I kept getting when attempting to open one of my projects. Hopefully, it isn’t already well known, and please keep in mind this may or may not work for everyone. I’m not tech savvy at all so bear with me.
I simply downloaded XML Copy Editor, then used it to open the Shotcut mlt. file I was having trouble with, and there I was able to clearly see the errors within the file itself - which in my case, was a missing string of numbers with “GS” as a placeholder.
Forunately, I had a much older backup of the same file that did work, so I opened both files in XML Copy Editor and found the missing numbers in the older file, then simply copied them into the latest file. I’m now able to open my project, and no longer receive the Failed to Open message.
You may or may not have an older backup of the same file like I do, so this solution may not work for you, but perhaps you will at least be able to see the errors in your file.