Most problems with a Project Zomboid server come down to a few causes. Start with the one that matches what you see.
Mods are downloaded but do nothing in game
Why: Only the Workshop item numbers were filled in. Downloading does not enable a mod.
Fix: Add each mod's Mod ID (the id= value in mod.info, not the title) to Workshop Mod IDs, then restart.
The Workshop Mod IDs field rejects what you typed
Why: You pasted the mod's display title (often with spaces) instead of its Mod ID, or used a separator other than a semicolon.
Fix: Use the id= value from the mod's mod.info or the 'Mod ID' on its Workshop page, separated by semicolons with no spaces.
Missing items or Lua errors after adding a mod
Why: Load order: a mod that needs a library or framework mod was listed before it.
Fix: Reorder Workshop Mod IDs so dependencies come first, then restart.
A Workshop item you listed was not applied (the console does not show it among the verified and applied items)
Why: Our server checks each Workshop item number at start and only uses the ones it could verify; an unavailable or wrong number is left out.
Fix: Check the number against the Workshop URL and that the item still exists on the Workshop, then restart and read the console lines that list the requested and applied Workshop items.
A setting you edited in the .ini or sandbox file is back to its old value after a restart
Why: The panel sets PVP, the player limit, RCON, Workshop items, mods, zombie population, zombie respawn, loot respawn and banned items from Settings, then Game Settings at every start.
Fix: Change those in Settings, then Game Settings instead. Other settings can be edited in the files while the server is stopped.
Your world seems to have vanished
Why: The Server Name variable was changed, which starts a separate world with fresh settings.
Fix: Set Server Name back to the previous value and restart; the old world is still on disk.
Players cannot join after a game update, or the world will not load
Why: Client and server are on different builds, or the world was made on a newer build than the server runs (for example after pinning an older Beta Branch).
Fix: Put the server and the players on the same build: turn on Steam Auto Update and restart, or ask support to change Beta Branch for you (b41multiplayer is the Build 41 branch), after a backup. If players still get file mismatch errors, have them verify game files in Steam.
You cannot raise Max Players
Why: The field is read-only and set by your plan.
Fix: Use Players on the server Overview page to lower the limit (up to your plan), or upgrade your plan to raise it.
You cannot log in as admin after changing the Admin Password
Why: The admin account is created on the first start. Changing the Admin Password afterwards may not change the existing account.
Fix: Log in with the password you used at the first start. If you are locked out, ask support.
Players are asked for a server password you never set
Why: The server password is not a panel setting. It is the Password line in the server settings file.
Fix: Stop the server, open <Server Name>.ini in .cache/Server in Files, clear the value after Password=, save, and start the server.
Still stuck?
Open a ticket in the category that fits and include the last 50 to 100 lines of the console. See How to open a support ticket and How to fix a server that will not start.
