“File Doesn't Match” and “Checksums Do Not Match” in Project Zomboid: What's Wrong and How to Fix It

What the game is checking

When you join, the server compares your game's Lua and script files, from the game and from every mod, with its own. If any of them differ, it won't let you carry on. It does this so nobody changes the rules with tampered files and so you're all playing the same thing.

It shows up in two ways. When joining, with “File doesn't match the one on the server” and the file's path. Or once you're in: it kicks you after a minute, and the server console shows Lua/script checksums do not match and reason="Lua incorrect checksum".

If what it says is that the server's version doesn't match yours, or “Workshop item version is different than server's”, that's a different problem: how to update the server.

The path in the error tells you what it is

If the path contains workshop\content\108600\ and a number, it's a Workshop mod: that number is its Workshop ID. Look for it in your mod list or put it in the address of a Workshop page to see which one it is.

If the path is in steamapps\common\ProjectZomboid, it's a file from the game itself: go to case 3. If it's in your Zomboid\mods folder, it's a mod copied by hand onto your PC: go to case 2.

If you get kicked after a minute and don't see any path, start with case 1, the most common.

Case 1: a mod has been updated

Workshop mods update whenever their author wants, even with the server running. The server keeps the version it downloaded on start and players arrive with another. A single mod is enough to kick the whole group.

1. Restart the server

   On start it downloads the latest version of every mod. This fixes most cases.

2. Have players restart the game

   Steam has to download the new version too. If a mod is pending in Steam's downloads, wait for it to finish before joining.

3. Join again

   If it still fails for just one person, go to case 2.

Case 2: it only fails for one player

They have a different copy of the mod from everyone else, nearly always from an unfinished download or a mod copied by hand.

1. Remove the mod

   On the Steam Workshop, unsubscribe from the mod in the path. If you don't know which it is, from all the server's mods.

2. Delete manual copies

   Check there's no folder with that mod in Zomboid\mods, in your user folder: that copy can clash with the Workshop one.

3. Join again

   When you connect, the game downloads what the server asks for again.

Case 3: the game's own files

If the path belongs to the game itself, or you edited a file by hand, let Steam repair it: right-click Project Zomboid → Properties → “Installed Files” → “Verify integrity”. It downloads whatever doesn't match again, including a file left half-finished by an update.

Also check you aren't on another branch: under “Betas” (in newer Steam, “Game Versions & Betas”) it should say “None”, unless the server is on another one on purpose.

Case 4: mods that run on Java

Some new mods aren't regular Workshop mods: they require ZombieBuddy or a manual install, and their page says something like “Mod ID: None (manual download)”. Those have to be set up the same way on the server and on every player; otherwise the server kicks everyone after a minute, even if they're in the mod list.

On your own server, you have to install them by hand on both sides. On a rented server, it depends on whether you're allowed to change the startup.

What if I turn off DoLuaChecksum?

DoLuaChecksum is the setting behind this check, and it's on by default. With DoLuaChecksum=false the message goes away, which is why half the internet recommends it, but it doesn't fix the difference: it just stops looking at it. The mismatched mods are still there, which can cause strange bugs and desync, and anyone can join with tampered files.

It doesn't let you play on different game versions either. Use it only briefly, to confirm that's the problem and find the mod, then turn it back on. More on what it protects in why the anti-cheat kicks you.

On NapNodes

First, “Home”: if Zomboid kicks someone for this, the panel recognises it in the console and explains it there.

1. Press “Restart”

   The server downloads the latest version of every mod on start. Then have players restart the game.

2. Remove Java mods

   Those that require ZombieBuddy don't work on our servers, because they don't include it: “Mods” warns you. Remove them there and restart.

3. If you have to turn off the check

   DoLuaChecksum is in “Settings” → “Anti-cheat and logs”. It takes effect on restart. Turn it back on once you've found the mod.

4. Change mods with a backup made

   Before touching many, create one in “Backups”. The free server has no backups: use “Download everything” in “Files”.

Frequently asked questions