So i just updated my cs:s server. My server loads fine but when it try to join it says "You do not have this third party mod installed". So i tried updating my steam client thinking it was that, Steam client is already up to date. Got any ideas?

I am not entirely shure, but as far as I remember this problem might be caused by the fact that for some reason your server didnt update right. Try updating the server again. That might work : )