Host a Project Zomboid Build 42 Server: Step-by-Step

Updated 7 November 2026 · Standard formula, shown below

This guide walks you through hosting a dedicated Project Zomboid server on Build 42, covering both Windows and Linux. You’ll set up the server files, configure the essential settings, and get your world running so friends can join. You’ll need a copy of Project Zomboid on Steam (for the dedicated server tool) and a machine with at least 4 GB of RAM and a decent CPU.

What You’ll Need

A Windows or Linux machine (dedicated server or your own PC) with at least 4 GB of RAM (8 GB recommended).
Project Zomboid purchased on Steam (the server files are free via SteamCMD or the Steam client).
SteamCMD (for Linux) or the Steam client (for Windows).
Port forwarding access to your router if players will join from outside your local network.

Step-by-Step

Install the dedicated server files.
- Windows: Open Steam, go to Library, and check the “Tools” dropdown. Find “Project Zomboid Dedicated Server” and install it. Alternatively, use SteamCMD with the command app_update 380870.
- Linux: Install SteamCMD (e.g., sudo apt install steamcmd on Ubuntu), then run steamcmd +login anonymous +app_update 380870 +quit. The files will download to your current directory.
Locate the server files. After installation, the server files are in a folder like steamapps/common/Project Zomboid Dedicated Server. Inside, you’ll find the executable ProjectZomboidServer.exe (Windows) or start-server.sh (Linux).
Run the server once to generate config files. Double-click the executable (or run the shell script). The server will start, generate default configuration files, and then stop. This creates the Server folder in your user directory (e.g., C:\Users\YourName\Zomboid\Server on Windows, or ~/Zomboid/Server on Linux).
Edit the server configuration. In the Server folder, find servertest.ini (the default name). Open it with a text editor. Key settings:
- DefaultPort=16261 – the game port (UDP).
- SteamPort1=8766 – Steam query port (UDP).
- SteamPort2=8767 – Steam master port (UDP).
- PublicName=Your Server Name – what appears in the server list.
- PublicDescription – a short description.
- MaxPlayers=16 – adjust to your preference.
- Pwd=YourPassword – set a password if you want a private server.
- SaveWorldEvery=15 – minutes between saves.
- ServerPlayerID= – leave blank for now.
Configure the map and sandbox settings. In the same servertest.ini, you can set Map= (e.g., Muldraugh, KY for the default map). For more detailed sandbox options (like zombie population, loot rarity), edit the SandboxVars section. If you want a specific map like Louisville, set Map=Louisville.
Start the server. Run the executable again. The server will load, generate the world, and display a console. Wait until you see “Server started” or similar. On Windows, you may need to allow it through the firewall.
Forward ports on your router. Log into your router’s admin panel, find port forwarding, and forward UDP ports 16261, 8766, and 8767 to your machine’s local IP address. This allows external players to connect.
Connect to your server. In Project Zomboid, go to Multiplayer > Join, and enter your public IP address (or your local IP if testing locally). If you set a password, you’ll be prompted.
Set up a dedicated server (optional but recommended). For a 24/7 server, consider using a separate machine or a VPS. The steps are the same, but you’ll need to keep the server running (e.g., using a screen session on Linux).

Common Mistakes

Not forwarding all three ports. Many guides only mention 16261, but Steam needs 8766 and 8767 to show the server in the list and allow connections.
Using TCP instead of UDP. Project Zomboid uses UDP only. Forwarding TCP will not work.
Editing the wrong config file. If you have run the server multiple times, you may have multiple .ini files. Make sure you edit the one matching your server name (default is servertest.ini).
Forgetting to allow the server through the firewall. Windows Firewall or your Linux firewall may block the server. Add exceptions for the ports.
Using a static IP vs. dynamic IP. If your IP changes, players won’t be able to connect. Use a dynamic DNS service or a static IP if possible.

Tips

Back up your save files. The world saves are in Zomboid/Saves/Multiplayer. Copy this folder regularly to avoid losing progress.
Set a server password. Even if you want a public server, a password helps prevent griefing.
Use the admin panel. In-game, type /admin to access admin commands. You can set yourself as admin in the servertest.ini by adding your Steam ID to AdminPw or using the addadmin command.
Adjust the save interval. Frequent saves reduce loss on crash, but may cause lag. A balance of 15-30 minutes works well.
Test locally first. Connect via your local IP to ensure the server works before sharing it publicly.

Troubleshooting

Server won’t start. Check the console for errors. Common causes: missing Java (Build 42 uses Java, install OpenJDK 17 or later), or the port is already in use. Run netstat -an | grep 16261 on Linux to check.
Players can’t connect. Verify port forwarding is correct, your firewall allows the ports, and you’re giving out the right IP (public IP for external, local IP for LAN). Also ensure the server is fully started (wait for “Server started”).
Server shows as offline on Steam. This usually means Steam ports (8766/8767) are not forwarded or the server isn’t using Steam networking. Check SteamPort1 and SteamPort2 in the config.
Lag or high ping. Ensure your internet upload speed is sufficient (at least 10 Mbps for 8+ players). Reduce MaxPlayers, or lower the server tick rate (not recommended). Also, make sure the server machine isn’t running other heavy tasks.
Server crashes on world save. This can happen if the disk is full or permissions are wrong. Ensure the Zomboid folder has write permissions. Also, check the logs in Zomboid/Logs for errors.

Frequently Asked Questions

Can I host a Build 42 server on a VPS with 2 GB RAM?

Technically yes, but it will be very laggy. Build 42 requires at least 4 GB, and 8 GB is recommended for a smooth experience with more than a few players.

Do I need to own Project Zomboid to host a server?

No, the dedicated server files are free, but you need a Steam account to download them via SteamCMD. The server itself does not require a game license.

How do I add admin to my server?

In the server console, type addadmin [SteamID] (without brackets). You can find your SteamID by typing /who in the game or using a SteamID finder online.

Can I change the map after the server has started?

Yes, but it will reset the world. Edit the Map setting in the config and restart the server. Be sure to back up your save if you want to revert.

Why is my server not showing in the public list?

Make sure Public is set to true in the config, and that Steam ports are forwarded. Also, the server may take a few minutes to appear. If it still doesn’t, check your firewall.

How do I update the server to the latest Build 42 patch?

Stop the server, run the update command (e.g., app_update 380870 via SteamCMD, or verify files on Windows), and restart. Your save files should be preserved.

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