[FATAL] Garry's Mod Server can't even initialize gamemodes

[_TheJok3r_]

Greetings forum!

You always helped me with specific problems, this one is definitely bigger.
I'm a Lua-Coder on a semi-big server, server is doing pretty well.

Once the server starts, the gamemode TTT isn't able to initialize itself.
cl_init:90 errors,
cl_popups:91 errors,
addon errors (almost every addon fails to init)

Unfortunately, I don't know why this happens, happened from one night to the next.
The new update may be the reason, due to those errors:

-attempt to index global: function x

Please help me out.
Have a good day.