crashed and lost all my work
Most of the time, if you save a file, a crash isn't a total loss. But today Musescore crashed, and now it says my file is corrupted and it won't open. So maybe best to recommend people save multiple copies under different names, so you don't lose a whole days work like I just did.
When starting to work on a file, I first make a new 'save as' with a new name before changing anything. During work I save this newly named file multiple times in all possible formats. I once had a total loss and never want to experience this again! But ... now with 4.0.2 all my precautions seem to be in vain. Had no problem whatsoever ... until now :-)