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FranciscoPombal wrote: ↑Tue Sep 22, 2020 6:18 pm It is possible that there was some problem migrating the .fastresumes from the old to the new version, and they could have even been deleted. .fastresumes are files that contain metadata that qBittorrent uses to keep track of torrents that are added to it. If they are deleted, qBittorrent forgets about the torrents, but no actual payload data is deleted from your hard drive. Check your files, they should all still be there.

However, this is still strange. Are you sure you weren't using a different profile/"portable mode"? It might also be the case that, 3.3.x being so old, between versions 3.3.x and 4.2.5 the .fastresume save location changed. If this is the case, the .fastresumes likely weren't even touched at all; 4.2.5 is simply looking for them in a new location that's different from the old one, and thus not finding anything.

At worst, you will have to manually add all torrents back to qBittorrent, but at least you haven't lost any actual data that you would need to re-download.

cloudtorrentseeker wrote: ↑Sun Sep 27, 2020 2:52 pm Hello and thank you for helping. I've found the .fastresume files!

They are at C:\Users\[username]\AppData\Local\qBittorrent\BT_backup and they are named like xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.fastresume.0, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy.fastresume.1, etc.

In the same folder there are equally numbered files named like xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.torrent, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy.torrent, etc. And also a file named "queue" (with no extension).

Where should I put these files to make qbittorrent recognize them and continue downloading?

tmlille79 wrote: ↑Thu Oct 01, 2020 7:06 pm same problem here. backed up my qbittorrent-folders both local and roaming, uninstalled 4.2.5 and reinstalled 3.3.1 again. All was still there luckily. Have to dig a bit deeper before trying again

FranciscoPombal wrote: ↑Sun Oct 04, 2020 4:20 pm They are in the correct folder, but they I don't why they have the ".0", ".1", ... at the end. Maybe that was a thing in those ancient versions? Nowadays, the fast resumes are just named xxxxxxxxxxxxxxxxxxxxxxxxxxxx.fastresume. You could try renaming them so that they no longer end in ".0", ".1", ... and see if that works (try with only one torrent first to see if it works).