Update your Project Zomboid server safely

OXY.Games Project Zomboid servers have Steam Auto Update enabled by default: on every start, the server checks for and installs available updates on its selected branch. Prepare your world before the next start, then verify the installed build and your players’ progress.

What you'll do

1. 1Record the current and target builds
2. 2Check saves and mods
3. 3Secure a recovery point
4. 4Check the startup update and test the result

A backup does not guarantee a return to the old build.

Restoring files also requires a compatible server build and the required mod versions. Check whether those versions remain available before changing anything; do not assume OXY can downgrade the server or automatically convert a save.

Prepare and check the update

1. Record both builds and branches

   Open your server’s Console and record the version in the startup log. In Startup, note Steam Branch and Server Name, then write down the exact build and branch you want next. A blank Steam Branch selects the stable branch; legacy41 selects Build 41. Compare the builds with the official release notes for 42.21 Stable and the notes for your target build. The branch setting alone does not prove which build is installed.

   Treat a patch and a save-breaking change differently. The developer says Build 41 saves cannot run on Build 42, and Unstable 42.19 saves cannot run on 42.20. Confirm save compatibility for your exact versions before proceeding. Do not use a newer server to test your only copy of an older save.

2. Check every mod against the target build

   Record your current Workshop items, Mod IDs, dependencies and map mods. Read each mod author’s support notes for the target build and existing saves. The mod installation guide explains PZ Mods and profile syncing; those mod actions do not update the Project Zomboid server software. If a required mod lacks a compatible version, pause the update or ask its author and OXY support about a safe route.

3. Make and inspect a recovery point

   Tell players when you plan to stop, then stop the server cleanly. Follow the panel backup guide, wait for completion and download a copy. Check its date and contents: the active world, character or account data, server profile and mod information must match the progress you want to keep. The world recovery guide explains how to check a recovery point before using it. If the copy is incomplete or cannot be checked, stop here and contact support.

4. Check Steam Auto Update before starting

   For a compatible update on the same branch, open Startup and check Steam Auto Update. The default 1 enables the server software update on every start; 0 disables it. Leave it at 1 if you want updates on later starts too. Do not change Steam Branch for this route. Starting the server triggers the update check, so complete the backup and compatibility checks first. Verify the installed build in the Console afterward; the setting alone does not prove an update succeeded. If your Startup page does not show this setting, ask support which update route applies. PZ Mods sync is a separate mod action, not a server software update.

   Changing Steam Branch requires a reinstall. Before changing it or reinstalling, send support your current and target branch, active profile, mod list and backup time. Ask what the installer changes in saves, accounts, configuration and Workshop files. Do not use Reinstall Server as a routine patch update.

5. Start, join and verify progress

   Start the server and read the Console for the installed build, startup completion and the first save or mod error. If the expected build was not installed, stop here and send support the current and target builds plus the first relevant update error. Use a matching client version to join with your original account name. Check the expected world and bases, then have affected players check their characters and inventory. If a check fails, stop changes and send support the build, backup time and first relevant error. Use the world recovery guide before any restore; a backup alone cannot supply an unavailable older server or mod version.

Done! The update has been checked.

Invite players back after the version, world and characters match your plan. Keep the downloaded recovery point until they have checked their progress; use the connection checks if someone still cannot join.

Extra tips

• Patch notes matter: a small version change can still affect mods; check the notes for the exact build you plan to install.
• Keep a change record: save the previous and new build numbers, branch, mod list and backup time together.
• Avoid a reset: the reset guide creates a new world; use it only when that is your goal.

Still stuck?

Send us your server name and the last 20 console lines. A real person reads it, usually within a few hours.

Open a ticket

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