The update didn't do much to the gamemode itself, but gmod servers have been breaking a lot in different ways. They've released a number of patches since the big update, so make sure you try to update the server's gmod version regularly. I just ran the update tool on my testserver and it updated gmod to version 86.
Can you see if there are any errors in the server console?
Are you using sv_downloadurl/fastdl? If yes, have you tried turning it off to see if that helps for the cl_init error?
I dont think I can see server logs, but I tried using fast dl before but it failed so I dont use it.
Edit: here is the error: