The crash report window told me to come here, but Windows troubleshooter already took control over the program and I couldn't even copy the text.
Here is some of it:
Btw, it seems that qBittorrent autmoatically deleted the files I was seeding.
qBittorrent crashed unexpectedly
Re: qBittorrent crashed unexpectedly
If you can reproduce the crash, please post an issue about it on GitHub.
Unlikely. Torrents removed from transfer list =/= files being removed from disk. Check if the files were actually removed from disk. It is possible for torrents to disappear from the transfer list, if qBittorrent crashes while handling/saving the .fastresume files it uses to track them.