GMOD SERVER WON'T UPDATE

[Twin]

My Server's Error: "The server you are trying to connect to is running an older version of the game"

My GMOD SRCDS server is not updating.
I'm using the STEAM CMD tool to update with this command line as a batch file:
steamcmd.exe +login anonymous +app_update 4020 validate +quit

I also tried another command line with the specified folder:
steamcmd.exe force_install_dir c:\newserver\ +login anonymous +app_update 4020 validate +quit

Everytime I update it loads in all the update stuff, and even files in my server files change, but it returns the same error that it is running an older version of the game.

Any help would be very appreciated!

It says, "App '4020' already up to date",
BUT returns the same error that it is running an older version of the game.

Please help.

[Nastyy]

I don't know if this is a sure fix, but I had the exact same problem. I ran the update file, and it downloaded an update, but then when I ran the file again after gmod said it was outdated, nothing updated. Well apparently I had downloaded the update to my garrysmod folder located inside my server folder instead of my server folder itself. I found the update named "garrysmod" inside my existing one so I merged the two. I hope this helps. ~ To be safe you might delete it and then redownload the update to the server folder

[Blaquicat]

Try without the validate option.

[TROPHIME]

For anyone who has a problem:
It's probably a rights issue, I solved the problem by running steamcmd as sudo user and it downloaded the update successfully.
Steamcmd has poor error handling, so it puts "already up to date" when it can't access/modify files.