How to Add Mods to a Project Zomboid Server (Build 42 and 41)

To add mods to a Project Zomboid server, stop the server and edit two lines in servertest.ini: WorkshopItems= gets each mod's Steam Workshop ID so the server downloads it, and Mods= gets each Mod ID so it switches on. On Build 42 every Mod ID needs a backslash in front, like Mods=\ModOne;\ModTwo. Map mods also go in the Map= line, before Muldraugh, KY. Start the server and players download the same mods when they join.

Short answer

WorkshopItems=2875848298;3490188370
Mods=\SomeModId;\AnotherModId
Map=SomeMapFolder;Muldraugh, KY

1. Stop the server.
2. Add the Workshop IDs to WorkshopItems=, separated by semicolons.
3. Add the Mod IDs to Mods=, separated by semicolons, with a backslash before each on Build 42.
4. For map mods, put the map folder at the start of Map=.
5. Start the server and watch the console for errors.

Where do I find the Workshop ID and Mod ID?

Every mod has two different IDs, and mixing them up is the number one reason mods do not load.

One Workshop item can contain several Mod IDs, for example a main mod and optional add ons. List the Workshop ID once, then only the Mod IDs you actually want switched on.

What changed in Build 42 for mods?

Build 42 became the stable branch on 29 July 2026, and mod loading changed in a few ways:

• The backslash. On Build 42, entries in Mods= take a leading backslash: Mods=\ModOne;\ModTwo. A Build 42 server skips entries without it. Build 41 uses plain IDs: Mods=ModOne;ModTwo.
• Mods need a Build 42 version. A Build 42 mod has a 42 folder (and often a common folder) inside it. A Build 41 only mod, without that, does not load on Build 42 at all. Check the Workshop page says it supports Build 42.
• Loot and sandbox keys changed. Mods that edit loot tables or sandbox values for Build 41 can break or do nothing on 42.
• Saves do not carry over. Build 41 worlds do not load on Build 42, modded or not.

If your group is attached to a Build 41 mod list, stay on Build 41 for that world. Servers can still install the legacy41 branch through SteamCMD:

steamcmd +login anonymous +app_update 380870 -beta legacy41 validate +quit

How does mod load order work?

The server loads mods in the order of the Mods= line, left to right. There is no automatic sorting on a dedicated server, so:

1. Frameworks and libraries first. Anything other mods list under "Required items" on the Workshop page goes at the front.
2. Big content mods next, such as vehicle packs or weapon overhauls.
3. Tweaks and patches last. A mod that patches another mod must load after it.

Map order works the same in Map=, but the base map goes last:

Map=RavenCreek;Muldraugh, KY

Leave Muldraugh, KY at the end, with the comma and the space exactly like that. Custom maps also usually need their Mod ID in Mods= and their Workshop ID in WorkshopItems=, not just the map folder.

How do I know if a mod failed to load?

Look in the server log (console.txt in the Zomboid folder, or the panel console). Common messages and what they mean:

When a big list breaks, remove half the mods, restart, and halve again until you find the culprit. Faster than reading every log line.

Do players need to install the mods?

No. Players do not need to subscribe first. When they join, the game downloads the mods the server lists. They do need to be on the same build as the server, and the first join on a big list takes a while.

How many mods can a server run?

There is no fixed limit, but each mod uses RAM and CPU, and map mods are the heaviest. A rough plan:

Keep the list lean. Every mod is another thing that can update and break joins, which is also a common source of server lag and rubberbanding.

Adding mods on a GamezServers server

You do not edit the ini lines by hand. In Settings:

• Paste Workshop IDs into Workshop IDs, separated by semicolons or commas.
• Paste Mod IDs into Mod IDs. We add the Build 42 backslash for you, so paste them plain.
• Put map folders in Map, map mods first and Muldraugh, KY last.

Press Backup, then Restart. The server downloads the mods on start, and the Check mod updates button tells you when a Workshop update needs a restart. Groups on a Build 41 mod list can pick the Build 41 (legacy) server type. Plans are on Project Zomboid server hosting, and the quick start covers the first setup.

FAQ

Why are my Project Zomboid mods not loading on the server?

Usually a Mod ID is missing from Mods=, a Workshop ID is missing from WorkshopItems=, or, on Build 42, the backslashes are missing. Check the server log for the mod name.

Do Build 41 mods work on Build 42?

Only if the author released a Build 42 version. Mods without a 42 folder do not load on a Build 42 server.

Can I add mods to an existing world?

Usually yes, after a backup. Removing mods from a running world is riskier, since items and buildings from them can vanish or cause errors.

Do I need to put the mod files on the server myself?

No. The server downloads everything in WorkshopItems= from Steam on start. Manual uploads are only for mods not on the Workshop.

Is the order of WorkshopItems important?

No. Only Mods= and Map= order matter. WorkshopItems= is just a download list.