Project Zomboid Build 42 (B42) Multiplayer – Server-Side Setup

Important Warning ⚠️

Build 42 Multiplayer is experimental.

• Bugs and crashes are expected

• Most Build 41 mods will not work

• Save incompatibility is possible

• Downgrading may require a full wipe

Only use Build 42 for testing or early-access servers.

Step 1: Find the Correct Beta Branch Name (Steam)

The beta branch name must match what Steam lists.

How to Verify (Steam Client)

1. Open Steam

2. Go to Library

3. Right-click Project Zomboid

4. Click Properties

5. Open the Betas tab

6. View the Beta Participation dropdown

Correct Branch for Build 42 Multiplayer

unstable

⚠️ This value is case-sensitive and must be entered exactly.

Step 2: Set the Beta Branch in Pterodactyl (Startup Tab)

You do not log into Steam on the server.
Instead, you set the beta branch in the Startup tab, and Pterodactyl passes it to SteamCMD automatically.

Steps

1. Open your server in the Pterodactyl panel

2. Go to the Startup tab

3. Locate the field for Steam Beta Branch
   (may be labeled something like BETA_BRANCH, STEAM_BETA, or similar)

4. Enter the following value:

   unstable

5. Save Changes

6. Reinstall the server (required)

Step 2: Start the Server

Once installation finishes, start the server normally.

⚠️ First startup may take longer due to:

• New map generation

• Asset rebuilding

• Engine changes in Build 42

Mods & Build 42 (Server-Side Warning)

Most Build 41 mods are not compatible with Build 42.

Server owners should:

• Disable all mods initially

• Add mods one at a time

• Only use mods that explicitly support Build 42

Mods may download successfully but still fail to load.

Switching Back to Build 41

If you want to return to Build 41:

1. Go to Startup

2. Clear the beta branch field (leave it blank)

3. Save changes

4. Reinstall the server

⚠️ Downgrading may require a world wipe.