SRCDS problem!

[Xyz]

Hello! I've searched a ton on this error, but I can't seem to find any kind of fix that works for me.

The game server I'm trying to run is Garry's Mod, it worked fine until an update around the end of 2015.
Here's the error:

Code:

Console initialized.
ConVarRef mat_dxlevel doesn't point to an existing ConVar
Game.dll loaded for "Garry's Mod"
Initializing Steam libraries for Workshop..
steamengine.cpp <2369> : Assertion Failed: pBaseUser
Assert< Assertion Failed: pBaseUser >:steamengine.cpp:2369

Bat file:

Code:

@echo off
cd c:\srcds\orangebox
cls
title srcds
start srcds.exe -console -game garrysmod +map gm_flatgrass +maxplayers 16 +gamemode sandbox +ip 192.168.1.148 +clientport 27015
goto srcds

This bat file does work fine for servers prior to the update (though I can't fully join them, as I am kicked out due to them running an older version)

I appreciate help of any kind.