I migrated to Ubuntu Wily last night and to my surprise, after starting QuiteRSS I saw my feeds were totally gone. No more feeds, no more folders. I found that my original feeds.db, cookies.dat and debug.log were in .local/share/data/QuiteRSS/QuiteRSS but QuiteRSS was looking for them in the .local/share/QuiteRSS/QuiteRSS. So I copied them where QuiteRSS was looking for them (.local/share/data/) and now this works fine.
The other problem is that now I have two QuiteRSS tray icons. I can live with that, but I would love to correct this, if someone knows how.
(Ubuntu 15.10 with Unity)