# Steam Workshop mods on a Project Zomboid server

How a Project Zomboid server loads Workshop mods: WorkshopItems against Mods, the Build 42 backslash, map folders and the order that mods load in.

Updated 2026-11-05.

A Project Zomboid server needs two lists to run a Workshop mod. `WorkshopItems=` holds the Workshop ID, the number Steam uses for the download. `Mods=` holds the Mod ID, the name the game uses to switch the mod on. Both lines live in the server's .ini file. On Build 42, each Mod ID starts with a backslash. Map mods need a third line, `Map=`, with their folder placed before `Muldraugh, KY`. Restart the server after any change, and players pick up the same mods when they connect.

## Why are there two different IDs?

Steam and the game think about mods in different ways. To Steam, a Workshop item is a package with a number. To Project Zomboid, a package can hold several mods, each with its own Mod ID. A vehicle pack might ship a main mod plus an optional extra in a single Workshop item.

So the server downloads by number and activates by name. Both values are printed near the bottom of the mod's Workshop page. The Workshop ID is also the number after `?id=` in the page address. If a mod author has more than one Mod ID listed, you only add the ones you want active. The Workshop ID goes in once either way.

| Line | What goes in it | Order matters? |
| --- | --- | --- |
| `WorkshopItems=` | Workshop IDs, separated by semicolons | No, it is only a download list |
| `Mods=` | Mod IDs, separated by semicolons | Yes, left to right |
| `Map=` | Map folder names, separated by semicolons | Yes, base map last |

## What does the Build 42 backslash do?

Build 42 changed how the server reads the `Mods=` line. Every entry needs a leading backslash, so a line that read `Mods=ExampleCore;ExampleTweak` on Build 41 becomes this on Build 42:

```
Mods=\ExampleCore;\ExampleTweak
```

A Build 42 server skips entries that lack it. The mod still downloads, but it never switches on. If you copied a mod list from an older guide or a Build 41 server, this is the first thing to check.

The backslash is not the only change. A mod also needs a Build 42 release to work on a Build 42 server. Inside the mod files, that shows up as a `42` folder, often next to a `common` folder. A mod made only for Build 41 will not load on Build 42 at all. The Workshop page usually says which builds it supports.

## How do map mods fit in?

A custom map usually needs all three lines. Its Workshop ID goes in `WorkshopItems=`, its Mod ID goes in `Mods=`, and its map folder name goes in `Map=`. The folder name is listed on the Workshop page as the Map Folder.

The base game map must stay at the end of the line, spelled exactly as the game expects, comma and space included:

```
Map=ExampleTown;Muldraugh, KY
```

Put two custom maps in, and both sit in front of `Muldraugh, KY`. Maps are among the heaviest mods for memory, so a server that runs fine with twenty small mods can struggle with two large maps.

## In what order should mods load?

The dedicated server loads `Mods=` from left to right and does no sorting of its own. A sensible order is:

1. Libraries and frameworks that other mods list as required.
2. Large content mods, like weapon or vehicle packs.
3. Small tweaks, translations and patches, with each patch after the mod it changes.

If a mod page lists "Required items", those must be in both `WorkshopItems=` and `Mods=`, and they belong further left than the mod that needs them.

## How do I find the mod that broke the server?

Open the server log, `console.txt`, and search for the mod's name or ID. A missing Mod ID, a typo or a missing requirement usually shows there. When the log does not make it obvious, take half the mods out, restart, and keep halving until the problem goes away. It is faster than guessing.

One error deserves its own mention: "Workshop item version is different than server's". It means a mod updated on Steam after the server started. Players already have the new copy, the server still has the old one. A restart fixes it.

## Do players have to subscribe to the mods?

No. When a player joins, the game reads the server's list and downloads what is missing. The first join on a long list can take a while. Players still need to be on the same build as the server.

## How this works on our servers

On a server from this site you do not edit the .ini lines yourself. In Settings, paste the numbers into **Workshop IDs** and the names into **Mod IDs**, separated by semicolons or commas. Paste Mod IDs without the backslash, since we add it on Build 42 and leave it off on the Build 41 type. Map folders go in **Map**, with `Muldraugh, KY` last. Press Backup, then Restart. The **Check mod updates** button tells you when a Workshop update means it is time to restart. Long mod lists run best on 8 GB or more, see [plans](https://projectzomboidservers.host/plans).

https://projectzomboidservers.host/guides/project-zomboid-server-workshop-mods