Project Zomboid Server Not Starting? Errors and Fixes
If your Project Zomboid server closes on startup or never gets as far as “SERVER STARTED”, the cause is almost always in the last lines of the console. In order of frequency: a mod (not made for Build 42, or missing another one), memory, a mistyped setting, a full disk or an update. Here's how to recognise each one and how to fix it, on your PC and on a rented server.
Where to see the error
On a dedicated server, in its console (the black window that StartServer64.bat opens, or the panel's “Console” if you rent it). What matters are the last lines before it stops: that's where the mod, the file or the memory error shows up. The server writes the same thing to server-console.txt, in the Zomboid folder in your user folder.
With “Host”, the game only says the server stopped during launch, with a reason in brackets; the most common one, NormalTermination, tells you nothing. The details are in coop_console.txt, in that same Zomboid folder (C:\Users\<your username>\Zomboid on Windows). Open it with Notepad and scroll to the end.
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A mod that isn't for Build 42 (or is missing another)
This is the number one cause, especially after moving to Build 42: Build 41 mods don't work on 42 and, if another mod depends on one that doesn't load, it fails too. A missing map mod is the worst: the world was generated with it. If the server starts but the mods don't load, check the backslash: on Build 42, Mod IDs are written as Mods=\ModName, and without it they don't load and nothing warns you (how to write both lists).
Make a backup
Before touching the mod list, copy the save folder: if the world uses a mod, removing it can leave holes (how to back up your save).
Look for the name in the console
If the last lines name a mod or a Workshop number, that's your suspect. Check on its Workshop page whether it's for Build 42 and what it lists under “Required items”.
Start without the last one you added
Remove it from WorkshopItems= and Mods= and start the server. If you don't know which one it is, remove them all except the maps and add them back a few at a time.
Put dependencies first
If a mod needs another, the other goes earlier in the list and has to be in both lines. The mod list tool writes the lines for you in order.
Out of memory (OutOfMemoryError)
If the console says OutOfMemoryError or Java can't reserve the memory, the server is asking for more RAM than it has. On your PC, it's set by the -Xmx in StartServer64.bat (on Linux, in ProjectZomboid64.json): lower it to what the PC really has free, or raise it if it falls short with lots of mods. With “Host”, it's the server memory setting on the hosting screen.
With Build 42, below 6 GB the server is very tight, and with a long list of mods or maps it needs 8 or more: how much RAM a Zomboid server needs.
A mistyped setting in the .ini or SandboxVars
If it stopped starting right after you edited <name>_SandboxVars.lua or <name>_spawnregions.lua by hand, it's almost always a missing comma or brace: they're Lua files and one typo stops them being read. Undo the last change, or go back to the copy of the file you made before touching it.
Always edit with the server stopped and one thing at a time: the .ini is rewritten on shutdown, and if you change ten things you won't know which one broke it. To avoid typing by hand, the Project Zomboid settings editor prepares the .ini and the SandboxVars in your browser.
“No space left on device”: the disk
The server won't start or won't save if the disk is full. Apart from the world, what grows most over time are the backups the game makes itself: by default one every time it starts and another when the version changes, and it keeps the last 5. Delete old ones or lower BackupsCount (which backups the game makes and where).
There's an odd case: the disk has space and you still get “No space left on device” on startup. On servers running in containers (as at many hosts), the game prepares the startup backup in a small temporary folder and, once the world grows, it doesn't fit. The fix is to turn off the startup backup (BackupsOnStart=false) and back up some other way.
After an update
If the server stopped starting right after a patch, it's usually a mod that hasn't been updated yet: remove mods as above and wait for the author to update it. If it starts but nobody can get in, it's the version: how to get the server and the players on the same one.
On a PC that had a Build 41 server and now has the Build 42 one, the official wiki describes a specific failure: it closes with “Assertion Failed: Illegal termination of worker thread”. The fix it gives: check that steam_appid.txt, in the server folder, has a single line with 108600, and if it still happens, copy the .ini, .lua and saves you want to keep somewhere else and delete the Zomboid folder in your user folder, which the server creates again.
If it stops while loading the world
If none of the above fits and the console hangs or crashes right as it loads the save (it sometimes happens after a power cut or a hard shutdown), it may be the save itself. To find out, move the save folder aside by renaming it and start the server: if it starts with a new world, the problem is the world. Put yours back and restore the last good backup. Resetting the world explains where that folder is.
With NapNodes
Java's memory is set automatically to your server's RAM on every start, so the -Xmx error won't happen to you. What can happen is the mod problem: in the “Mods” tab, remove the last one you added and click “Restart”; the panel already adds Build 42's backslash and warns you about mods that another one needs and are missing (“Add the missing ones”).
Check the “Console” to see the error. If you edited a file by hand, it's in “Files”, in .cache/Server (napnodes.ini, napnodes_SandboxVars.lua…); and settings can be changed without typing anything in “Settings”. If the save is broken, in “Advanced settings” → “Backups” you have the automatic daily backup and your own. On the free server the disk is 15 GB and you get an email at 80% and at 95%; it has no panel backups.
If none of this fixes it, open a ticket in “Help” with the last lines of the console. And as a last resort, “Reinstall server”, at the bottom of “Settings”, runs the game installation again (make a backup first).
Frequently asked questions
What does NormalTermination mean when a Project Zomboid server stops during launch?
That the “Host” server closed on startup without saying why. The reason is at the end of coop_console.txt, in the Zomboid folder in your user folder; it's almost always a mod or the server memory.
Why won't my Project Zomboid server start with mods?
Because a mod isn't for Build 42, is missing a dependency or they're in the wrong order. Remove the last one you added and start it; if you don't know which, remove them all except the maps and add them back a few at a time.
Where is the Project Zomboid server log?
In the Zomboid folder in your user folder: server-console.txt for the dedicated server and coop_console.txt for “Host”. On a rented server, in the panel's console.
My Zomboid server says “No space left on device” but the disk isn't full
It's usually the backup the game makes on startup, which doesn't fit in the temporary folder. Turn off BackupsOnStart in the .ini and back up some other way.
Why did my server stop starting after an update?
Almost always because of a mod that hasn't been updated for the new version yet. Remove the mods, check that it starts and add them back.
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