Comment 3 for bug 1873949

I figured out how to manually set this to be looked at again: I figured I ought to explain a bit more, and I am sorry for disrupting your process: it feels pretty invasive.

The error only occurs when doing bulk ebook processing, and windows showed me no errors or warnings about possible virus attacks. Windows defender is the only antivirus-like program I permit to run on my computer: and I look at Task Manager often enough to say for certain that another one didn't get installed. I don't even have ransomware protection set up!

Further, I have been running calibre for a while, and ran some really massive ebook-polishing jobs with it. Jobs that involved several hundred books that were in the tens of megabytes. I only recently updated to the 4.0 branch, and that was the first time I saw this error (also, the first time I used this specific option in a bulk processing: but that is a bit beside the point).

It's because of those things that I am almost completely certain that this bug is some sort of thread race: the line encountering the error is attempting to rename a set file (based on method names: I don't really speak advanced python), which strongly implies to me that, as 8 threads attempt to rename one file, windows says "one at a time!" and denies the rest access.