How to Change Project Zomboid Sandbox Settings on an Existing World

To change Project Zomboid sandbox settings on an existing server world, stop the server, edit Zomboid/Server/<servername>_SandboxVars.lua (servertest_SandboxVars.lua by default), and start it again. Most values, like XP, zombie lore and loot multipliers, apply to the world you already have, but loot only changes in containers nobody has opened yet. The trap: the save keeps its own copy of the sandbox in map_sand.bin in Saves/Multiplayer/<servername>/. If your edit is ignored, back it up, delete it, and start again.

What you can change on an existing world

Server rules like PVP, Password and MaxPlayers are not sandbox settings. They live in <servername>.ini and always apply on the next start.

Where are the sandbox files?

The Zomboid folder is C:\Users\<you>\Zomboid\ on Windows and ~/Zomboid/ on Linux. Hosts often point it elsewhere with -cachedir, and the server name is whatever the server starts with in -servername.

Step 1: Back up first

Copy the whole Saves/Multiplayer/<servername> folder and the three files in Server/ that start with your server name. A sandbox mistake you can undo in two minutes is not a mistake.

Step 2: Stop the server properly

Type save and then quit in the server console, or use your host's stop button. Do not edit while the server runs. Project Zomboid writes its settings files back out when it shuts down, so anything you changed while it was running is overwritten by the values it had in memory.

Step 3: Edit the SandboxVars file

Open <servername>_SandboxVars.lua. Values sit inside one big table:

SandboxVars = {
    VERSION = 6,
    Zombies = 4,
    Distribution = 1,
    XpMultiplier = 2.0,
    WaterShutModifier = 30,
    ElecShutModifier = 30,
    ...
    ZombieLore = {
        Speed = 2,
        Strength = 2,
        ...
    },
}

Most numbers are positions in the in game dropdown, not real amounts: Zombies = 4 is the fourth population choice in the menu, and Speed = 2 is the second speed option. WaterShutModifier and ElecShutModifier are days. Keep every comma and brace. A broken file makes the server fall back to defaults.

The safest way to get the right numbers is to build the settings in the game's own sandbox menu (Host > Manage Settings), save them, and copy the matching lines out of the file it writes in Zomboid/Server/.

Step 4: Start and check

Start the server, join, and check something you can see, such as the XP multiplier or zombie speed. Admins can open the Admin panel in game and look at Sandbox Options to read the live values.

Step 5: If nothing changed, reset map_sand.bin

This is the step other guides leave out. The save stores its own sandbox copy in map_sand.bin, and when that file is stale or damaged (crashes are a common cause), the server keeps using it and your Lua edits never show up. Admins on the Steam forums traced exactly this problem to the file.

1. Stop the server.
2. Download map_sand.bin from Saves/Multiplayer/<servername>/ and keep it with your backup.
3. Delete it from the server.
4. Check your _SandboxVars.lua once more, then start the server.

The server builds a fresh map_sand.bin from your Lua file. Your map, players and vehicles are in other files and are not touched.

Changing settings from the admin panel

Admins can also change sandbox values in game from Admin > Sandbox Options and apply them without a restart. It is handy for a quick test, but admins report the change does not always survive a restart. For anything permanent, put the same value in the Lua file with the server stopped.

Common problems

• Your edit vanished after the restart: you edited while the server was running, and it wrote the old values back on shutdown. Stop, edit, start.
• The server ignores the file completely: a stale map_sand.bin in the save folder, or you edited a file for another server name. Check the name matches -servername.
• Loot is still scarce after raising it: the towns you have visited already generated their containers with the old values. New areas get the new loot.
• Power is still off after pushing the shutoff later: the shutoff day had already passed in this world. Use generators, or start a new world with the date you want.
• A brand new world appeared: the server started with a different server name, so it made a new save. Your old one is still in its own folder.
• Settings reset to default: a missing comma or brace broke the file. Restore your backup and edit again.

Changing sandbox settings on GamezServers

On a GamezServers Project Zomboid server, the files are in .cache/Server and named after the Save name setting (GamezServers_SandboxVars.lua on a new server), and the world is in .cache/Saves/Multiplayer/GamezServers/. Press Backup, Stop, edit the file in the Files tab, then Start. The panel rewrites a few .ini keys on every start (password, player cap, public listing, whitelist, mods and map), so change those in Settings, but it never touches your sandbox file. Changing Save name starts a separate world, and the old one stays on disk. For values worth using, see the best Project Zomboid server settings.

FAQ

Can I change Project Zomboid sandbox settings without starting a new world?

Yes. Edit <servername>_SandboxVars.lua with the server stopped and start it again. Only the start date and the time since the apocalypse need a new world.

What is map_sand.bin in Project Zomboid?

It is the save's own copy of the sandbox settings. Deleting it with the server stopped makes the server rebuild it from your Lua file without touching the world.

Why are my Project Zomboid sandbox settings not saving?

You probably edited the file while the server was running, and it wrote its old values back when it shut down. Always stop the server first.

Do loot changes apply to an existing world?

Only to containers that have not been generated yet. Areas players have already visited keep the loot they rolled with the old settings.