After switching from 3.0 to 3.0.1 an attempt to save the file results in an endless waiting for the "save window" to complete an operation(I have alot of space and 3.0 saved the very same file fine) and if I hit close on that window I can open various menus and dialogs(including right-button mouse docker with brushes and colors selector and ability to pan and zoom the picture) but brushes won't draw at all and the cursor is in a "waiting' state. But worst of all any click on any save option(save, save as, export) wont do a thing. If I try to close Krita after that it crashes and delete an autosave with it. I'm using win7 if it is important. It is really irritating and deal-breaking behaviour so I have to switch back to 3.0 since loosing hours or so of work isn't fun at all. Reproducible: Sometimes
maybe it is somehow related to this bug: https://bugs.kde.org/show_bug.cgi?id=369014 At least the description sounds very similar besides the fact in my case it doesn't matter which format do you save to.
Could you see if you can create a backtrace of said crash? https://docs.krita.org/KritaFAQ#How_can_I_produce_a_backtrace_on_Windows.3F The other one is on OSX, so it might be a different issue.
Does this only happen with that specific file? If so, could you share it with us?
Can confirm this bug on krita 3.0.1.1. This happened a few times with one very big file and once with "normal" file. After that I switched back to 3.0
*** This bug has been marked as a duplicate of bug 370566 ***