How to Make a Project Zomboid Build 42 Server

Requirements and backup

Prepare a non-administrator service account, SteamCMD, enough storage for the installation and backups, and access to the firewall and router. The dedicated-server AppID is 380870. The game client does not need to be installed on the server.

If a Zomboid user folder already exists, stop the process cleanly and copy that whole folder off the machine. It contains saves, server profiles, logs and player databases. Do not load a Build 41 world directly in Build 42.

Install and start Build 42

1. Install SteamCMD in its own directory.
2. Download the server on Windows with steamcmd +force_install_dir C:\pz-server +login anonymous +app_update 380870 validate +quit. On Linux, use a path owned by the service account.
3. Run StartServer64.bat on Windows or StartServer64.sh on Linux. The first start creates the servertest profile and takes longer than a normal restart.
4. Set a unique administrator password when prompted. Once generation finishes, stop the server cleanly before editing anything.
5. Open Zomboid/Server/servertest.ini. For a public server, check at least Open=true, Public=true, PublicName, MaxPlayers, and a join Password when the group is private.

The profile name follows -servername. A launch option such as -servername friends creates friends.ini, friends_SandboxVars.lua and friends_spawnregions.lua; editing servertest.ini would then have no effect.

Ports and first validation

Current Build 42 documentation lists UDP 16261, UDP 16262, and—depending on the Steam networking path—UDP 8766 as the default set. Allow them through the host firewall and forward them to the server's fixed private address when it sits behind a router. Do not expose RCON if you do not use it.

Validate in this order:

1. connect over the LAN using the private address;
2. confirm that the client and server show the same Build 42 version;
3. test from another network with the public address and port 16261;
4. create a character, leave, restart and verify that both character and world persist;
5. read the logs before adding mods.

Direct connection working while browser discovery fails usually points to public-list settings or Steam discovery. A LAN failure is more likely to involve the process, selected profile or version. The server-not-showing guide provides a decision tree.

Mistakes to avoid after installation

• Never edit or copy a live world while the server is writing it.
• Do not treat MaxPlayers as a capacity guarantee; mods, world activity, memory and CPU matter.
• Validate a vanilla start before enabling a mod list.
• After a Steam update, update the server and clients before troubleshooting the network.
• Automate a graceful shutdown, an off-server backup and scheduled restarts.

To avoid router and operating-system maintenance, compare Project Zomboid server hosts, paying particular attention to file access and save exports.