Project Zomboid servers can crash or fail to start for several well-known reasons. This guide covers the most common causes seen across Legion Hosting support tickets — from a Build 42 memory bug that requires extra RAM on startup, to a backup overflow that fills /tmp, to corrupted configuration files. Work through the sections below in order.

Before You Begin — Locate Your Crash Logs

Almost every Project Zomboid crash leaves evidence in one of two places. Check both before attempting any fix, so you know which section of this guide applies to you.

GPanel Console Output

1. Log in to GPanel.
2. Select your Project Zomboid server from the server list.
3. Click the Console tab.
4. Scroll to the bottom of the output. Look for lines marked ERROR, FATAL, OutOfMemoryError, or Exception. The last 20–30 lines before the server stopped are usually the most relevant.
5. If the console is empty, the server process terminated before it could write anything — this is itself a clue (see the B42 memory section below).

The Server debug.log File

Project Zomboid writes a detailed log to debug.log in the server's data directory. This file often contains a full Java stack trace that points directly to the crash cause.

1. In GPanel, go to the File Manager tab.
2. Navigate to /.cache/Logs/. You will see files named like debug.log, DebugLog-server.txt, or dated log files.
3. Open the most recent log file. Use Ctrl+End or scroll to the very bottom and read upward from there.
4. Look for the keywords OutOfMemoryError, IOException, NullPointerException, or SandboxVars. Copy the relevant lines — you will need them if you open a support ticket.

Fix 1 — Build 42 High Memory Usage on Startup (Known Game Bug)

If your server exits immediately on startup with no error in the console, or the console shows OutOfMemoryError or a Java heap space error, the server is running out of memory before the world finishes loading.

Symptoms

• Server starts, console scrolls for a few seconds, then stops with no player-facing error.
• Console shows java.lang.OutOfMemoryError: Java heap space or GC overhead limit exceeded.
• Server works on some restarts but not others (memory availability varies).
• Server ran fine on B41 but crashes consistently after upgrading to B42.

Steps

1. In GPanel, click your server and go to the Console tab. Note your server's current RAM allocation shown in the resource bar or server info panel.
2. If your plan includes less than 10 GB RAM, the server may crash during startup because B42 requires approximately 9 GB to initialize. You will need to upgrade your plan or wait for the Indie Stone to release a fix.
3. If your plan already has 10 GB or more and the server still crashes on startup, go to the Startup tab in GPanel.
4. Look for a field labeled Java Memory, Max RAM, or Xmx. Confirm it is set to no more than 80–85% of your total available RAM. For example, on a 12 GB plan, set this to 10240 (10 GB in megabytes). Do not set it equal to or above your total RAM — the operating system and other processes also need memory.
5. Click Save on the Startup tab, then restart your server.
6. Watch the console during startup. If the server reaches the line SERVER STARTED or LuaManager: Loading lua files... completes without crashing, the memory allocation is now sufficient.

Fix 2 — BackupsOnStart Overflowing /tmp (Startup Crash)

Project Zomboid can be configured to create a full world backup every time the server starts. When this backup is written to /tmp — which is limited in size on most Linux hosts — the server crashes mid-startup with a disk write error once /tmp fills up.

Symptoms

• Server crashes reliably on every restart, but was working previously.
• Console or debug.log contains errors like IOException: No space left on device or mentions writing to /tmp/.
• Crashes tend to get worse over time as the world save grows larger.
• Server sometimes starts if you try shortly after a clean reboot of the host node (before /tmp fills again).

Steps — Disable BackupsOnStart

1. In GPanel, go to the File Manager tab.
2. Navigate to /.cache/server/. Look for your server configuration file — it is typically named servertest.ini or whatever your server name is followed by .ini (e.g., MyServer.ini).
3. Open the .ini file for editing.
4. Use your browser's find function (Ctrl+F) to search for BackupsOnStart.
5. Change the value from true to false:

   BackupsOnStart=false

6. While in the file, also check the BackupsOnVersionChange setting and set it to false if disk space is a concern:

   BackupsOnVersionChange=false

7. Save the file and restart your server. Monitor the console to confirm the server reaches the SERVER STARTED line.

Fix 3 — Corrupted SandboxVars.lua or Server Config

Project Zomboid stores world settings in a Lua file called SandboxVars.lua. If this file is edited manually and saved with a syntax error, or if a file transfer was interrupted, the server will crash immediately on startup when it tries to parse the file.

Symptoms

• Console shows ERROR: SandboxVars, LuaManager error, or a Lua parse error with a line number.
• The crash started happening right after you edited settings in the .ini file or SandboxVars.lua directly.
• The server may show Bad argument #1 to or similar Lua runtime errors.

Steps — Check and Repair SandboxVars.lua

1. In GPanel, go to File Manager and navigate to /.cache/saves/multiplayer/<YourServerName>/.
2. Open SandboxVars.lua for editing.
3. Check that the file starts with VERSION = 1, (or similar) inside a SandboxVars = { block, and ends with a closing }. Any missing comma, unclosed brace, or stray character will cause a parse failure.
4. If you cannot identify the error, the safest fix is to delete SandboxVars.lua entirely. The server will regenerate it with default values on the next startup. Note: this resets your sandbox settings (loot, zombie count, etc.) to defaults — your map data and player data are not affected.
5. Also check the .ini file in /.cache/server/ for similar issues if you recently edited it by hand. Ensure every line follows the Key=Value format with no blank lines inside a value.
6. Save changes and restart the server.

Fix 4 — Empty Admin Password Causing Crash

Project Zomboid requires a non-empty admin password to start a multiplayer server. If the password field is blank, the server process exits immediately after attempting to initialize the admin account.

Symptoms

• Brand new server or recently reset server fails on every start attempt.
• Console output is very short — the server prints a few initialization lines and then stops.
• debug.log may contain a reference to the admin account or password validation.

Steps

1. In GPanel, click your server and go to the Startup tab.
2. Look for a field labeled Admin Password or RCON Password. Confirm it contains a value — it must not be blank.
3. If the field is empty, enter a password. Use at least 8 characters. Avoid special characters like !, #, $, or @ in the admin password, as some PZ versions fail to parse them correctly in the startup arguments.
4. Click Save and restart the server.
5. As a secondary check, open the .ini file in /.cache/server/ and confirm the line AdminPassword= has a value after the equals sign.

Fix 5 — Reset the World (Last Resort for Persistent Crashes)

If a world save becomes corrupted — for example after a hard server crash, a failed update, or file system errors — the save data itself may be unrecoverable. In this case, deleting the world and starting fresh is the only option.

Steps

1. Stop your server in GPanel before making any changes to the save files. Editing files on a running server can cause further corruption.
2. In GPanel, go to the File Manager tab.
3. Navigate to /.cache/saves/multiplayer/.
4. You will see one or more folders with your server name (e.g., servertest). Before deleting, optionally download the folder as a backup by selecting it and using the download option — even a corrupted save may be partially recoverable later.
5. Delete the folder matching your server name inside Multiplayer/. Do not delete the Multiplayer folder itself.
6. Also navigate to /.cache/db/ and delete the <YourServerName>.db file. This database holds player statistics and may reference the old world — regenerating it avoids mismatches.
7. Start your server. It will generate a fresh world using the settings in your .ini file.

Quick Diagnostic Reference

Still Crashing After All Steps?