These errors mean Garry's Mod couldn't talk to Steam when it started. Close Steam fully, open it again, sign in, and launch the game from your Steam library. That fixes most cases.
If it doesn't, the sections below cover every cause Valve lists for this failure.
Why Garry's Mod Can't Reach Steam
Valve's Steamworks documentation lists the reasons a game fails to connect to Steam on startup:
- Steam isn't running.
- Steam can't tell which game is starting, usually because you didn't launch it from Steam.
- The game and Steam are running as different Windows users, or one runs as administrator and the other doesn't.
- The Steam account that's signed in doesn't own the game.
Every fix on this page deals with one of those.
Failed to Initialize Steamworks API
Close Steam Completely
Click Steam in the top left and choose Exit. Then open Task Manager with Ctrl + Shift + Esc and end any Steam process still listed.
Open Steam and Sign In
Start Steam and wait until your library loads. If Steam is in offline mode, click Steam and choose Go Online.
Launch From Your Library
Start Garry's Mod with the Play button in your Steam library. A shortcut that points straight at the game's .exe can skip Steam's handshake.
Restart Your PC
If it still fails, restart your computer. That clears stuck Steam processes and file locks.
Players often report this error on the 64-bit branch. If you're on it, try the fixes from the 64-bit guide's troubleshooting section. Switch Betas to None, let it update, then switch back to x86-64.
Steam Error: No SteamUser
No SteamUser means the game started but Steam didn't hand it a signed-in account. The fix is the same as above: close Steam fully, sign back in, and launch from your library.
If that doesn't work, check these:
The game and Steam must run with the same rights. Go to your game folder (right-click Garry's Mod, Manage, Browse local files). Right-click the game's .exe, choose Properties, open Compatibility and untick Run this program as an administrator. Do the same for Steam if you set it there.
The account that's signed in must own Garry's Mod. If you play it through Steam Families, another family member may already be using the shared copy.
Right-click Garry's Mod, choose Properties, go to Installed Files and click Verify integrity of game files.
Reinstall Steam over the top of your current install. Download the installer from store.steampowered.com/about and install it to the same folder. Valve says this keeps your installed games. Uninstalling Steam any other way deletes them.
Couldn't Load Library
If Garry's Mod says it Couldn't Load Library, verify your game files first. If the error stays, another program may have put copies of the game's own files into Windows.
Facepunch's fix is to rename these files if you find them in C:\Windows\System32\ or C:\Windows\SysWOW64\:
steam_api.dllbass.dllAwesomium.dll
Add .old to the end of each name. Facepunch says this doesn't harm Windows or the program that put them there. Don't touch any other file in those folders.
Steam or Garry's Mod Not Up to Date
Garry's Mod won't start properly while Steam or the game itself is waiting on an update.
Update Steam
Click Steam in the top left and choose Check for Steam Client Updates. Let it download, then restart Steam.
Update Garry's Mod
Open the Downloads page at the bottom of your library. If Garry's Mod is queued or paused there, start the update and let it finish.
Servers have their own version messages, such as The server is out of date. Another is The server is running a newer version of the game. You can't fix those from your side, and you can't downgrade Garry's Mod. Wait for the server to update, or play somewhere else until it does.
If you're on the dev branch, it can run ahead of normal servers just before an update. Set Betas back to None to match them.
Steam Authentication Errors on Servers
Some errors kick you from a server because it couldn't confirm your Steam account. You might see:
STEAM validation rejectedNo Steam logonSteam auth ticket has been canceled
The server asked Steam who you are and didn't get a valid answer.
Check You're Online in Steam
Your Steam status should show online, and Steam shouldn't be in offline mode. Sign out of Steam and back in if it looks wrong.
Restart Steam and the Game
Exit both fully, start Steam, then start Garry's Mod from your library.
Wait a Few Minutes
Steam's servers sometimes drop out for a short while. Wait five to ten minutes and try again.
Turn Off a VPN
Valve lists VPNs, firewalls and some antivirus tools as programs that can stop Steam reaching its network. Turn off your VPN and try again.
If it only happens on one server, tell its staff.
Other Steam Problems
- Game won't open at all, or Steam says it's already running? See Garry's Mod Won't Launch.
- Game opens and then crashes? See Fix Garry's Mod Crashing.
Want a server to try it on? Justified is a Garry's Mod DarkRP server: justified.gg.
