Search and open a file named: urls.py inside the XBMCtorrent addon folder, in Linux the path to it is usually –

/home/<USER-NAME>/.xbmc/addons/plugin.video.xbmctorrent/resources/site-packages/xbmcswift2/urls.py

Go to line 110 where it says: items[key] = quote_plus(val)

and change it into: items[key] = quote_plus((val).encode('utf-8'))