Left 4 Dead (2) maps not working/crashes Gmod

Title pretty much describes my problem.
Left 4 Dead maps won’t start up. 1’s maps crashes the game before they even start up, and 2’s maps won’t even load at all.
It would be most appreciated if I could get help with this problem.

If you’re loading them straight from the game through mounting them to Garry’s Mod, they simply won’t work. They are built on a different version of the Source Engine than Garry’s Mod and have a lot of entities/props/etc. that the Garry’s Mod engine can’t handle because they don’t exist.
I’m sure that people have uploaded working version of the maps into Garry’s Mod on the workshop, you’ll just have to look for them.

L4D2/Portal 2/CS:GO uses a different map format ( and they specify a different BSP version ), so it simply does not work.

L4D1(and new TF2 maps) uses a different different map format, but does not specify a different BSP version, so when GMod tries to load the map, it crashes.

You cannot get help with this problem, neither this problem can be fixed by you. There’s no set date to when this problem is going to be fixed, it is very unlikely that it ever will be fixed.

That gotta cover all the questions you may have.