I was trying to search for keywords in the 'General Discussion' section in the Last.fm official forum, but it would show Something went wrong with the search. It’s not your fault. Give it another go? for any keyword I search for. Why does this happen?
Most likely, the search function is no longer available on those old groups. It doesn't work on any groups from old site, not just for that particular forum. Since groups are not re-implemented on the new site, it's no wonder such useful function as searching on old groups is also not functioning.