Arma 3 Server Version Mismatch: How to Fix It

Updated 7 November 2026 · Standard formula, shown below

If you see a “server version mismatch” error when joining an Arma 3 server, the fix is to make your game version match the server’s version. This usually means updating Arma 3 to the latest stable release, opting into the same beta branch (like “Stable” or “Legacy”), and checking that your mods are the same versions as the server’s.

What Causes a Version Mismatch?

Arma 3 uses a version number that includes the game build and the DLC/expansion pack. When you connect, the server sends its version to your client. If they don’t match exactly, you get the mismatch error. Common causes:

You’re on an older or newer game build than the server.
The server runs a beta branch (e.g., “Stable” vs “Development” or “Legacy”).
Your mods have different versions than the server’s mods (even if the mod names are the same).
Your game files are corrupted or not fully updated.

Quick Fix: Update Arma 3 to the Latest Stable Build

Open Steam and go to your Library.
Right-click Arma 3 and select Properties.
Go to the Updates tab.
Under “Automatic updates,” select Always keep this game updated.
If the game is already updated, try Verify integrity of game files (in the Local Files tab).
Restart Steam and launch Arma 3.

If the server is running a different build (e.g., a public beta), you’ll need to opt into that same branch.

How to Join a Specific Beta Branch

Some servers run on beta branches—especially those using the “Legacy” build for older mods or the “Development” branch for testing. To match:

In Steam, right-click Arma 3 → Properties → Betas tab.
From the dropdown, select the branch the server uses. Common options:
- None – the default stable build.
- Legacy – for older mods or servers that haven’t updated.
- Development – for testing new features (rarely used by public servers).
Close the window and let Steam download the selected branch.
Launch Arma 3 and try joining again.

If you’re not sure which branch the server uses, check the server’s description or website. Most public servers run the stable build.

Mod Version Mismatch: The Most Common Culprit

Even if your game version matches, mods can cause a mismatch if their versions differ. Arma 3 checks the mod’s mod.cpp file for a version number. If the server has a newer or older mod than you, you’ll get a mismatch.

How to fix:

Find the server’s mod list (usually shown in the server browser or on their website).
In your Steam Library, go to Arma 3 → Workshop → Subscribed Items.
Ensure every mod is updated. Right-click the game → Properties → Updates → Always keep this game updated also applies to workshop mods.
If a mod is outdated, unsubscribe and resubscribe to force a fresh download.
If the server uses mods from a third-party launcher (like a custom repo), you may need to use that launcher to sync mods.

Using a Launcher to Auto-Sync Mods

Many servers use a mod launcher (like Arma 3 Launcher, Play withSIX, or a custom one). These launchers can automatically download and update the exact mod versions the server uses. If you join a server that requires a specific launcher, install it and use it to launch the game instead of the Steam button. The launcher will handle version matching for you.

Still Getting the Error? Advanced Steps

If the above doesn’t work, try these:

Clear your Arma 3 cache: Delete the Arma 3 folder in Documents (back up your profiles first). This resets settings but can fix corrupted configs.
Check for Windows firewall/antivirus: Sometimes they block the connection, but that usually gives a different error. Still, ensure Arma 3 is allowed.
Reinstall the game: Uninstall, then reinstall Arma 3. This is a last resort but fixes any corrupted files.
Check server status: The server might be running a development build that isn’t public. Contact the server admin for the exact version.

Frequently Asked Questions

Why does the server show a different version than mine?

Because the server’s game build or mod versions are not the same as yours. This can happen if the server admin hasn’t updated the server, or if you’re on a beta branch.

Do I need to uninstall mods to fix a version mismatch?

No, you just need to update them to the same versions as the server. Unsubscribing and resubscribing often forces an update.

Can I join a server with a higher version than mine?

No. Arma 3 requires an exact match. You must update your game to the server’s version.

What if the server uses a “Legacy” build?

You’ll need to opt into the Legacy beta branch in Steam (Properties → Betas → select “Legacy”). This is common for older modpacks.

Why do I get a version mismatch even after updating?

Usually because your mods are outdated. Check each mod’s version against the server’s list. Also, verify that you’re not running extra mods that the server doesn’t have.

Is there a way to see the server’s version before joining?

Yes, in the server browser, you can often see the game version and mod count. Some servers list the version in their mission description or website.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.