I know this is meant to be in the support thingy but i don't know how so herre goes
Whenever i try to get onto the hallway server it just crashes and the note that pops up says 'Server timeout: version mismatch or map transfer fail.' what does that mean??

The game may possibly be full.

Moved to Support.

As StackOverflow said, the server may have been made full while you were connecting.. or, as the error says, there might have been an error transferring the current map from the server to your computer.
It's worth checking the player count on the list before trying to connect, and if it's not full and you get the error, it's worth trying to connect a few times, and try connecting to other servers.

ALSO, a quick note. Some people actually have a terrible internet connection to these servers, and this will cause the connection to the server download to time out.

You are also frequently plagued by lag spikes and "you might have been kicked" messages.

I should know because i use a sprint hotspot for internet.