Weird Gmod srcds error.

Hello, today when I booted up my server, I attempted to start up my server with this command (Like always):

c:\KKServer\orangebox\srcds.exe -console -game garrysmod -hostport 27015 +maxplayers 32 +map gm_construct

And for some reason, it wouldn’t boot up at all. It would crash with this message in the the window:

Reading externally referenced elements is not supported.

Can anyone help me out?

Try updating the server content. Move the addons out of the addons folder.(Make the addons folder empty). If it works, then put the addons back in. And try again.