Is it an almost instantaneous error, or does it take some time to happen?
If it's instantaneous, then I suspect it's PHP crashing when it tries to do a specific (very common) thing with MySQL. I don't know how to resolve it - presumably you just upgraded PHP or haven't installed XF on this server before. It is something within PHP/MySQL that we can't touch.
If it takes a while (as in the linked thread), then it's that damn slow I/O sort of thing. I've not really seen it on that particular step though. It may go through after some tries.