Online play - Incorrect version

So I'm trying to play EF with a friend of mine, but we can't join each other's games! Whenever I invite him I get an error saying he has an incorrect version of the game. We're both running with the latest EF patch, and I've played online with other people, so I'm pretty sure my online functionality is just fine.

Is this a known problem?

Do you and your friend installed all the updates (1.21~1.23.2) or just the 1.20 full version??

It would seem that my friend had botched his updates. We managed to fix it! Thanks for your quick reply though :)

Problem fixed, thread locked.