Project Zomboid Build 42 has officially reached the Stable branch, giving server owners a more permanent version to move to after the long Unstable testing period.

If you run a Project Zomboid server yourself, switching versions is not quite as simple as updating the game through Steam. You need to make sure the dedicated server is using the correct branch, update the installation through SteamCMD, and check that your server configuration is ready for Build 42.

This guide walks through the full process from a beginner's perspective, including the exact SteamCMD commands and server locations you may need.

Can You Transfer An Existing Server Save To Build 42 Stable?

Before changing your server version, it is important to understand that existing saves are not compatible with Build 42 Stable.

Build 41 saves cannot be transferred to Build 42.

Build 42.19 Unstable saves are also not compatible with Build 42.20 Stable. This is because Build 42.20 introduced additional changes that prevent those older Unstable worlds from being carried forward.

If you want to continue playing an older world, you would need to remain on the game version that supports that save. When moving your server to the current Project Zomboid Build 42 Stable branch, you should expect to create a new world.

You may still want to back up your existing server files before making any changes, but this is for preserving the old installation and save data rather than transferring the world into Build 42 Stable.

On Windows, Project Zomboid commonly stores dedicated server data inside:

C:\Users\YourUsername\Zomboid\

Multiplayer saves can normally be found in:

C:\Users\YourUsername\Zomboid\Saves\Multiplayer\

Server configuration files are stored under:

C:\Users\YourUsername\Zomboid\Server\

If you want to preserve the old server, copy the entire Zomboid folder somewhere safe before continuing.

Stop Your Project Zomboid Server

Before updating any server files, completely stop your Project Zomboid server.

If you currently have the dedicated server console open, shut the server down normally and wait for the process to fully close.

You should avoid updating the installation while the server is still running because some files may still be in use.

Once the server is offline, you can begin updating the dedicated server installation.

Open SteamCMD

SteamCMD is Valve's command-line tool for installing and updating dedicated game servers.

If you already self-host a Project Zomboid server through SteamCMD, you should already have a folder containing:

steamcmd.exe

Open the SteamCMD folder and double-click steamcmd.exe.

A command window will appear. Commands can be entered directly into this window.

Start by logging in anonymously:

login anonymous

Project Zomboid's dedicated server files can be downloaded without signing into a personal Steam account.

Set Your Project Zomboid Server Installation Directory

SteamCMD now needs to know where your existing Project Zomboid dedicated server is installed.

For example, if your server files are stored in:

C:\PZServer

enter:

force_install_dir C:\PZServer

Replace C:\PZServer with the actual location of your dedicated server.

If you are unsure which folder this is, look for the directory containing your Project Zomboid server files and startup script, such as:

StartServer64.bat

It is important that force_install_dir points to your existing server installation. Otherwise, SteamCMD may install another copy of the dedicated server into a different folder.

Switch From Build 42 Unstable To Stable

When Build 42 was still on the Unstable branch, self-hosted server owners had to specifically tell SteamCMD to install that beta branch.

An Unstable update command may have looked similar to this:

app_update 380870 -beta unstable validate

Project Zomboid Dedicated Server uses Steam App ID:

380870

Now that Build 42 is on the public Stable branch, you no longer need the -beta unstable argument.

To update the server to the current Stable version, enter:

app_update 380870 validate

SteamCMD will then download the latest public Stable files and check the existing installation.

Once the update has finished successfully, enter:

quit

If you use an automatic update script or .bat file, check that as well.

For example, if your updater still contains:

-beta unstable

remove that part from the command. Otherwise, the next time your updater runs, it may attempt to install the Unstable branch again.

Start Your Build 42 Stable Server

Once the update has completed, return to your Project Zomboid dedicated server folder.

On a normal Windows installation, the server can usually be started using your .bat file, for example:

StartServer64.bat

Allow the server to finish loading and watch the console for any errors.

If you are moving from Build 41 or Build 42.19 Unstable, remember that you will need to create a new Build 42 Stable world rather than loading the previous save.

You should also review your Workshop mods before adding them back to the server, as some of them may not be stable-branch ready.

Build 41 mods are not automatically compatible with Build 42, and some older Build 42 Unstable mods may also require updates before they work correctly on the latest Stable version.

Adding outdated mods immediately can make it much harder to determine whether a startup problem is being caused by the server itself or by a mod.

How To Switch To Build 42 With Project Zomboid Hosting

Using dedicated Project Zomboid hosting removes much of the manual SteamCMD and file management required when self-hosting.

With Pine Hosting, open the Project Zomboid server you want to update and go to the Startup tab.

Find the setting called:

Steam Beta Branch

If you previously used Build 42 Unstable, this field may currently contain:

unstable

Build 42 Stable now runs on Project Zomboid's default public Steam branch, so you should remove unstable and leave the Steam Beta Branch field empty. You do not need to enter stable, public, or another branch name.

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If you wish to create a backup of your previous world, this point would be the final chance. You can create it by going to the Backups tab and click on "Create Backup".

Once the Steam Beta Branch field is empty:

  1. Go to Settings in your server panel.
  2. Click Reinstall and select "delete all server files and reinstall".
  3. Wait for the Project Zomboid server files to reinstall.
  4. Start the server once the installation has finished.

Reinstalling the server with no beta branch selected installs the current public Stable version of Project Zomboid.

Remember that switching the server installation does not make an older world compatible with Build 42 Stable. If you are moving from Build 41 or an incompatible Build 42 Unstable version, you will need to start a new compatible world.

Compared with self-hosting, there is no need to open SteamCMD, find the Project Zomboid Dedicated Server App ID, remove -beta unstable from commands, or manually update the installation. You simply remove the old beta branch from the panel and reinstall the server.

Start Your Build 42 Server With Pine Hosting

Build 42 brings major changes to Project Zomboid, but managing the technical side of a dedicated server does not need to be complicated.

With Pine Hosting's Project Zomboid hosting, you can manage your server, change Steam branches, reinstall server files, configure your setup, and control your server directly through one panel.

Whether you are starting a new Build 42 world with friends or preparing a larger modded community, dedicated Project Zomboid hosting can save you from having to manually manage SteamCMD and the underlying server installation.

Start your Project Zomboid Build 42 server with Pine Hosting and begin your new Build 42 world today.