How to Add Mods to a Project Zomboid Server
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Project Zomboid server mods come from the Steam Workshop: the server loads them, and players download them automatically when they join. Setting them up comes down to two lines in the server settings — but each line wants a different kind of ID, and Build 42 changed how mods are packaged.
This guide covers both IDs, where they go, Build 42 versus Build 41, maps, load order and updates, plus what to check when a mod does not load.
How Project Zomboid server mods work: Workshop ID and Mod ID
- Workshop ID — the number at the end of the mod's Steam Workshop address, for example
2169435993. It tells the server what to download. - Mod ID — the name the mod uses inside the game, written on the Workshop page (usually near the bottom, as Mod ID:) and in the mod's
mod.infofile. It tells the server what to load.
One Workshop item can contain several mods, each with its own Mod ID. Add only the Mod IDs you want — often the page tells you which one to pick.
Add mods from the panel instead of hunting for files: HytHost Project Zomboid hosting from €6.54/mo.
See Project Zomboid plansAdd mods in servertest.ini
The server settings file is Zomboid/Server/servertest.ini (named after your server). Stop the server, then fill in two lines:
WorkshopItems=2169435993;2392709985 Mods=ModA;ModB
WorkshopItems— Workshop IDs, separated by semicolons, with no spaces.Mods— the Mod IDs from those items, also separated by semicolons.
Start the server. It downloads the Workshop items and loads the mods, and players get them automatically when they connect.
Build 42 or Build 41: what changes for mods
Build 42 is the current stable version (42.21); Build 41 is still available as a legacy branch for older mod lists.
- Mods are built for one build or the other. A Build 42 mod has its files in a
commonor42folder; a Build 41 mod does not. Some Workshop items contain both. A mod that is not made for your server's build is skipped. - The backslash. Build 42 shows Mod IDs with a backslash in front, like
\ModA. On a Build 42 server you can write them with or without it — the server removes it. On a Build 41 server never add one: there it becomes part of the name and the mod is not found. - Check the Workshop page for which build a mod supports before you add it, and keep the whole list on one build.
Map mods and load order
Maps need a third line. Besides the Workshop ID and Mod ID, add the map's folder name to Map=, keeping the base map in the list:
Map=MyMapFolder;Muldraugh, KY
The map's Workshop page gives the folder name and where it should go in the list — follow it, especially when you combine several maps.
Load order follows the order of Mods=. If a mod requires another one, the server loads that requirement first by itself — but only if it is installed, so its Workshop ID has to be in WorkshopItems as well. A mod whose requirement is missing is skipped.
Keeping mods updated
When a Workshop mod updates, players download the new version, but the server keeps the old one until it restarts — and a player whose copy no longer matches can have trouble joining.
- Restart to update. On every start the server downloads any Workshop item that is missing or out of date.
- Check without restarting: the admin command
checkModsNeedUpdateasks Steam whether any of your items changed and writes the answer to the chat and the log. It only reports; it does not update anything. - Warn players and restart when it reports an update, ideally on a schedule.
When a mod does not load
- Wrong ID in the wrong line — Workshop IDs (numbers) belong in
WorkshopItems, Mod IDs inMods. - Spaces or a missing semicolon in either list.
- The mod is for the other build — check the Workshop page; on Build 41, remove any backslash.
- A requirement is missing — add the required mod's Workshop ID and Mod ID too.
- Read the log — the server writes which mods it loaded and which it skipped, and why.
Mods on a HytHost Project Zomboid server
- Put the IDs in the Startup tab. It has a field for Workshop items and one for Mods. The panel writes them into
servertest.iniat every start, so add mods there — mods typed straight into the file are replaced at the next start. - Maps are the exception: edit the
Map=line inservertest.iniwith the file manager. - Restart from the panel. The server downloads the mods on start, and the game itself is updated before each start too.
- Choose the build when you order: Build 42 or the Build 41 legacy branch. Switching later is a reinstall, so take a backup first.
The rest of the server settings are explained in Project Zomboid server settings, and plans are on Project Zomboid hosting.
Build 42 or Build 41, mods from the Startup tab, automatic backups — Project Zomboid hosting from €6.54/mo.
See Project Zomboid plansFrequently asked questions
The Workshop ID is the number in the Steam Workshop address and goes in WorkshopItems. The Mod ID is the mod's name inside the game, from the Workshop page or mod.info, and goes in Mods. A server needs both.
No. Build 42 shows Mod IDs with a backslash, but a Build 42 server accepts them with or without it. On a Build 41 server never add a backslash, or the mod will not be found.
No. Players download the server's Workshop mods automatically when they connect.
Restart the server: it downloads updated Workshop items on every start. The command checkModsNeedUpdate tells you whether an update is waiting, but does not install it.
Usually a Workshop ID in the Mods line or the other way round, a missing requirement, or a mod built for the other build. The server log lists which mods were skipped and why.
Your mod list, running for the whole group
HytHost Project Zomboid hosting runs Build 42 or Build 41 with Workshop mods from the Startup tab and automatic backups — from €6.54/mo.
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