Necesse Server Version Mismatch or Can't Connect (Fixes)

When Necesse players cannot join a dedicated server, the most common cause is a version mismatch: the game updated through Steam and the server did not. Update the server (many setups leave auto update off), restart it, and everyone connects again. The other usual suspects are mods that do not match exactly between server and players, a beta branch on one side only, UDP port 14159 not reachable, and a wrong password or full slots.

Cause 1: The server missed an update

Necesse left Early Access with 1.0 in October 2025 and still gets regular patches. Players update automatically through Steam. A dedicated server only updates when told to, and it will not accept a client on a different version, so the game tells the player the versions do not match.

Update a self hosted server with SteamCMD:

steamcmd +force_install_dir /home/necesse/server +login anonymous +app_update 1169370 validate +quit

Then restart. On Windows, use your server folder path. If the server runs from a start script that does not update, add this step before launching, or make a habit of running it whenever a Necesse patch is announced.

Many hosted setups have auto update switched off by default so a patch never surprises you mid session. That is sensible, but it means you must update by hand after every patch, or players get locked out.

Cause 2: Beta branch on one side

If you opted the server into a beta branch to try a test build, players must switch to the same branch in Steam (right click Necesse, Properties, Betas). The reverse is common too: one friend on the beta, everyone else on the stable release. Version mismatch messages that only hit one player usually come down to this.

Cause 3: Mods do not match

Necesse checks mods when you connect. The server and every player must have the same mods, in the same versions. If they differ, the game lists the mismatch instead of letting the player in.

1. Compare the .jar files in the server's mods folder with what each player has subscribed on the Workshop.
2. After a Necesse update, mods often update too. Players get the new mod version through Steam, but the server keeps the old .jar until you upload the new one.
3. A mod that has not been updated for the new game version can stop the server loading at all. Remove it until the author catches up.

Our Necesse mods guide shows where Workshop mods are stored on your PC and how to copy them to the server.

Cause 4: Port not reachable

Necesse uses UDP 14159 by default (the port in cfg/server.cfg). For a server you host at home:

• Forward UDP 14159 to the server's local IP.
• Allow Java (the server runs on Java) through the firewall.
• Check for CGNAT: if your router's WAN IP differs from your public IP, forwarding will not work. Hosting without port forwarding covers this.

Players add the server under Multiplayer, Add server, with the address and port as separate fields. A wrong port there looks exactly like a blocked one.

Cause 5: Password or slots

Cause 6: The world will not load after an update

Rarely, a big patch and an old mod together stop a world from loading. Restore a backup taken before the update, remove the outdated mod and try again. If you did not take one, start making it a habit before every update. See how to back up a game server.

A patch day routine

1. See a Necesse patch in the Steam news.
2. Stop the server and take a backup.
3. Update the server.
4. Update the mod .jar files on the server to match what the Workshop now serves.
5. Start the server and check the console for errors.
6. Tell your group to restart Steam before joining.

Avoiding the lockout

On a GamezServers Necesse server, Steam Auto Update is a panel switch. It is off by default, so turn it on if you want each restart to pull the latest build, or leave it off and restart with it on after a patch. Steam Beta Branch is a panel field for test builds, the mods folder and cfg/server.cfg are in the file manager, and one click backups make the before update snapshot easy. The server has its own address with the port open. For the basics, see how to host a Necesse server.

FAQ

Why does Necesse say my version does not match the server?

The server is on an older or newer build than you. Update the server and restart, and make sure you are on the same Steam branch.

What port does a Necesse server use?

UDP 14159 by default, set in cfg/server.cfg.

Do Necesse mods need to match the server?

Yes. Every player needs the same mods in the same versions as the server, or the connection is refused.

Does a Necesse server update itself?

Only if auto update is on. Many setups leave it off, so update after every patch.