"Cannot Read File"

Musescore updated today to Musescore 3, and I am working on a show for Drum Corp. Where I go to open MuseScore, I get the set up wizard, and all of my "recently opened" scores are gone. When I click on my file for my show, I get a "Cannot Read File" error screen. This only happens with the score I created today, not in previous versions. There was no crash, no bug, no power outage or anything. Is there a way I can get my file to work?