Update server might be stuck at 2.0.4.34, per Update to 2.0.4.35 not offered #4012 (see testing notes). Unless somehow some people are getting the update, I guess manual install would be the workaround.
2.0.4.36 Canary “Fatal” OneDrive 404 not found error after backup #4015 is a new style of error (no previous reports that I can find of the details), but it’s not clear when it was added, or if it will repeat. Because of update server issues, 2.0.4.35 (and its OneDrive work) might not have had wide uptake
EDIT: Possibly a rare random glitch. Problem has not repeated, and another person couldn’t get it…