// project zomboid · waitlist

Project Zomboid server hosting: Build 42 waitlist

DSN Servers doesn’t sell Project Zomboid servers yet. We’ll only open them after testing Build 42 servers with popular Workshop mods, and only if enough groups ask. This page is the waitlist, plus what The Indie Stone and the PZwiki document about running a modded Build 42 server, which works wherever you host yours.

Updated October 2026  ·  Build 42.21 (stable) and Build 41 (legacy41)  ·  Dedicated server

What we’d do for your group

If we open Project Zomboid servers, the server itself is the easy part. The work is the mod list, so that’s the part we’d take on:

• Set up and test your Build 42 mod list. You send your Steam Workshop collection, or the list of mods you want. We add each one by its Workshop ID and mod ID, start the server, and check that every mod loads before your group joins.
• Mods by Workshop ID, not a re-uploaded pack. The server downloads each mod straight from the Steam Workshop, so mods stay up to date and their authors keep control of them. The Indie Stone’s modding policy says a public modpack needs permission from every included mod’s author, and suggests a Workshop collection instead, so we wouldn’t bundle anyone’s mods into a pack of our own.
• The right branch. Build 42 stable for a new world, or the legacy41 beta branch for a group that wants to keep its Build 41 world and mods.
• Help when it crashes. When a game or mod update breaks the server, we read its console log, find the mod that broke, and roll it back or swap it out.
• Steam Workshop mods only, unless you ask. The Indie Stone supports Lua mods. Java mods change the game’s own code, aren’t officially supported and break when the game updates, as its note on Java mods (October 21, 2026) explains, so we’d go through the risks with you before installing one.

Where this stands

What Build 42 changed for servers and mods

• Stable since July 29, 2026. The Indie Stone moved Build 42 (version 42.20) to the public stable branch that day, and released 42.21 to stable on September 28. The Indie Stone says new versions should now go to the Unstable branch for testing first, then to Stable.
• Build 41 saves don’t carry over. The Indie Stone’s Build 42 checklist says Build 41 savegames aren’t compatible with Build 42. A Build 41 server that updates starts a new world.
• Build 41 lives on as a beta branch. Server owners and players who want to stay on Build 41 can switch to the legacy41 beta. The server and its players have to be on the same branch.
• Mods need a Build 42 layout. Build 42 loads a mod’s files from a common folder and a version folder (42, or a later one such as 42.12), and a mod needs at least one of them to show up in the game. A mod with only the Build 41 layout, its media folder at the top, isn’t loaded (PZwiki: Mod structure). Authors can ship both layouts in one Workshop item, so check each mod’s Workshop page for Build 42 support instead of guessing from its age.
• Java mods are on their own. Java mods usually need a separate loader or a manual install, not just a Workshop subscription. They aren’t officially supported, and game updates break them without warning.

How a dedicated server loads Workshop mods

A dedicated server keeps its settings in servertest.ini, or <name>.ini if you start it with -servername <name>. It lives in ~/Zomboid/Server on Linux and %USERPROFILE%\Zomboid\Server on Windows. These lines load mods:

WorkshopItems=1111111111;2222222222

Those two IDs are made up. A Workshop ID only downloads a mod; the mod does nothing until its mod ID is on the Mods= line too.

The safe way to fill in Mods= is to let the game write it: in Project Zomboid, open Host, then Manage Settings, add the mods under Steam Workshop and Mods (and any map under Map), save, and copy the .ini it writes to your server.

• Players don’t install anything by hand. When they connect, the game downloads the server’s Workshop mods for them.
• Open the ports. UDP 16261 and UDP 16262 by default, set by DefaultPort= and UDPPort= in the same file.
• Set the admin password on the first start. The server asks for it in its console the first time it runs.
• Restart after changing mods, and add a few mods at a time, so when one breaks the server you know which.

How much RAM a Zomboid server needs

We won’t give per-player numbers until we’ve measured our own test server. What’s documented: the server’s memory is set by the -Xms and -Xmx values in its start script, and the PZwiki’s dedicated server page says Windows’ StartServer64.bat asks for 16 GB by default. A machine without that much free memory fails to start the server, so set both values to what you can spare, for example -Xms6g -Xmx6g for 6 GB.

Moving a server from Build 41 to Build 42

1. Decide whether to move at all. Your Build 41 world won’t load in Build 42. To keep playing it, stay on Build 41: install the server from the legacy41 branch with SteamCMD, and have every player pick legacy41 under Game Versions & Betas in the game’s Steam properties.

   app_update 380870 -beta legacy41 validate

2. Back up the server’s .ini and .lua files in Zomboid/Server and its world in Zomboid/Saves/Multiplayer, even if you’re starting fresh. You’ll want the settings.
3. Update the server to the stable build (380870 is the dedicated server’s Steam app ID):

   app_update 380870 validate

4. Rebuild the mod list. Check every mod’s Workshop page for Build 42 support, drop or replace the ones without it, then add the rest a few at a time.
5. Start the new world. If a machine that ran a Build 41 server stops with Assertion Failed: Illegal termination of worker thread, the PZwiki’s fix is to check that steam_appid.txt holds only 108600, then, after backing up, delete the old Zomboid folder so Build 42 recreates it.

Sources

• The Indie Stone: Build 42.20 released (July 2026), Build 42 checklist, 42.21 stable released, a note on Java mods and the modding policy.
• PZwiki: Dedicated server, Server settings and Mod structure, read on October 22, 2026.

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