First, I’d be willing to bet that you have a slash/ in your file name. Remove it & you’ll be fine. Unix does not like filenames with slashes in them. If you want, you can replace the slash with an underscore_ or a hyphen-.
Second, you really need to save a lot more often than every 40 minutes. Personally, I reflexively save anytime I get something the way I like it, any time that I decide to go back & try something different, or any time I decide to change gears & move on. Autosave is not a replacement for being careful & methodical. The people who complain about autosave not working right are always the ones who go hours on end without saving their work.
Arnie
https://www.arniepix.com