Server Won't Start or Keeps Going Offline

Common Causes and Solutions

If your server shows "Starting" then immediately goes back to "Offline", work through these checks in order.

1. Read the Console Output

The most important step. Go to the Console tab and read the error message. Look for lines containing ERROR, FATAL, or a Java stack trace. The error tells you what went wrong.

Also check the /crash-reports folder in your Files tab — Minecraft writes detailed crash reports there with the exact cause.

Common errors:

• "Unable to access jarfile server.jar" — The server file is missing. Go to Settings → Reinstall (back up first), or use the Version Changer to re-download it
• "EULA not accepted" — Check the Startup tab and set the EULA variable to true. Or open eula.txt in the Files tab and change eula=false to eula=true
• "OutOfMemoryError" — Your server is running out of RAM. See Step 4 below
• "Failed to bind to port" — Another process is using the port, or the port is misconfigured. Try restarting. If it persists, contact support
• A mod or plugin name in the error — That specific mod/plugin is crashing the server. See Step 3

2. Check Your Version

• If you recently changed versions, ensure your mods and plugins are compatible with the new version
• Java version mismatch: Minecraft 1.17+ requires Java 17. Minecraft 1.20.5+ requires Java 21. Running the wrong Java version produces a specific startup error. Check the Startup tab for the Java version setting
• When in doubt, set the version to latest and reinstall

3. Isolate Problem Mods/Plugins

If the error points to a mod or plugin:

1. Remove or rename the suspected file in the /mods or /plugins folder
2. Restart the server
3. If it starts, that file was the problem. Check for a compatible version or alternative
4. If it still does not start, continue removing recent additions one by one

Tip: For large mod lists, use a binary search — remove half the mods at once, test, then narrow down which half contains the problem. This is much faster than removing one at a time.

4. Check RAM Usage

• Remove mods and plugins you do not need to free up resources
• Review your configuration — large view distances, excessive entity spawning, and chunk loaders consume significant resources
• Only consider upgrading your plan if you have already cleaned up your configuration and the issue persists

5. Restore from Backup

If nothing else works:

1. Go to the Backups tab
2. Restore the most recent working backup
3. Start the server

Still Not Working?

Copy the full error from your server console and open a support ticket. The error message helps us diagnose the issue much faster.