Problem with UTF characters

[porphyry5]

qbittorrent 2.9.3 on slackware 13.37

The torrent concerned starts to download but immediately produces a qbittorrent error message "invalid or incomplete multibyte or wide character", and then goes into a Paused state.

Is there any way to get around this problem?  I've downloaded from other torrents that produced files with multibyte characters with no difficulty.

[Peter]

I'm not familiar with Slackware's package management, but could you update the client to a newer version?
(To be honest, I wanted to use Slack, but the install took soooo long, I just gave up. =))