Project Zomboid Build 42 Dedicated Server Setup (42.21 stable)
Build 42.20 went stable on 29 July 2026. B42 is no longer a beta branch you opt into, it is the supported build, and Project Zomboid passed its all-time peak player count the day it landed. If anything below describes B42 as unstable or upcoming, read it as history: the branch it refers to is now the default. The one live caveat is mods, since a lot of Workshop items have not been republished for stable yet, so a list that worked last week can fail today.
Build 42 is the biggest Project Zomboid update in years, and since 42.20 it is the default public build: you no longer opt into a beta to run it. The Unstable beta still exists and now carries 42.21 ahead of public, so opt into it only if you want that. Use this guide to spin up a Build 42 server, keep any Build 41 server intact, and avoid common multiplayer pitfalls. If you would rather not maintain two SteamCMD installs by hand, a managed Project Zomboid dedicated server installs Build 42 for you without touching the command line.
Important: Build 41 and Build 42 saves are not compatible, so a Build 41 world needs its own server on the Build 41 legacy branch rather than an upgrade.
Planning Checklist
| Task | Reason |
|---|---|
| Clone a new server directory | Keep Build 41 and Build 42 separated |
| Backup saves and configs | Build 42 saves cannot downgrade |
| Review mods | Many mods are not Build 42 ready |
| Match client branch | Every player must be on the same build as the server |
Step 1: Install Build 42 with SteamCMD
Build 42 is on the public branch, so no beta flag is needed. Example:
steamcmd +login anonymous +force_install_dir /opt/pz-b42 +app_update 380870 validate +quitIf you use a hosting panel, the stable option already installs Build 42.
Step 2: Configure Server Settings
Server settings live in Zomboid/Server/ as servertest.ini (or your custom name). Common settings to adjust first:
ServerName=Build 42 Test
MaxPlayers=16
Public=false
Password=
PVP=false
WorkshopItems=
Mods=
Use a separate server name so players can clearly identify the Build 42 test environment.
Step 3: Review Mods Carefully
- Disable non-essential mods until Build 42 compatibility is confirmed.
- Keep
WorkshopItemsandModslists aligned. - Update mods before every server restart.
Step 4: Launch the Server
Use the standard start script for your platform, but point it to the Build 42 install and server name. Example (Linux):
./start-server.sh -servername "servertest"On Windows, launch StartServer64.bat and select the same server name.
Step 5: Keep Clients Synced
Every player needs the same build as the server. A client that has not opted into any beta is already on Build 42; a client still on the Build 41 legacy beta, or on Unstable while the server is on public, will get a version mismatch error when connecting.
Troubleshooting
Server starts but players cannot join
Confirm the server and the clients are on the same build. Re-run SteamCMD updates if needed.
Mods cause startup crashes
Disable mods, start the server once, then re-enable mods one at a time.
Save file errors
Start a fresh Build 42 world. Build 41 saves will not load correctly.
Related Guides
- How to access Build 42 unstable
- Build 42 feature overview
- Complete server settings
- Enable whitelist and access control
Need a reliable test environment? Host your Project Zomboid server with Supercraft and swap branches in minutes.