Troubleshooting

Running into issues with your Minecraft server? This guide covers the most common problems and their solutions. Check the relevant section below before reaching out for support.

Server Will Not Start

EULA Not Accepted

Symptom: Server stops immediately after starting with a message about the EULA.

Solution: Open eula.txt in the File Manager and change eula=false to eula=true. See our Accepting the EULA guide.

Out of Memory

Symptom: Console shows java.lang.OutOfMemoryError or the server crashes during startup.

Solution:

If running a modpack, check that your plan has enough RAM. Heavy modpacks (100+ mods) need at least 8GB, and some need 16GB.
Remove any mods or plugins you are not using.
Consider upgrading to a higher plan (The Reactor at 8GB or The Mainframe at 16GB).

Port Already in Use

Symptom: Console shows Failed to bind to port or Address already in use.

Solution: This usually resolves itself within a few seconds. If it persists, wait 30 seconds and try starting again. If the issue continues, contact support.

Corrupted Server JAR

Symptom: Console shows Error: Invalid or corrupt jarfile or ClassNotFoundException.

Solution:

Stop the server.
Delete the server JAR file (e.g., server.jar, paper.jar).
Go to the Startup tab and re-trigger the download by saving the settings.
Start the server again.

Invalid server.properties

Symptom: Server crashes with errors referencing server.properties.

Solution: Delete server.properties and restart the server. A fresh file will be generated with default values. Then reconfigure your settings.

Connection Issues

”Can’t Connect to Server” / “Connection Refused”

Possible causes:

The server is not running. Check the console in your dashboard at Dashboard.
You are using the wrong address or port. Verify both from your server’s overview page.
The server is still starting up. Large modded servers can take 3-5 minutes to fully start.
If using a custom domain, DNS may not have propagated yet. Try connecting with the direct IP and port.

”Connection Timed Out”

Possible causes:

Your internet connection may be blocking the port. Try from a different network.
The server may be overloaded and not responding to new connections.
Check the server console for errors.

”Outdated Server” or “Outdated Client”

Symptom: The client version does not match the server version.

Solution: Either update your Minecraft client to match the server version, or change the server version to match your client. See Changing Server Version.

”Failed to Verify Username” / “Authentication Servers Are Down”

Possible causes:

Mojang’s authentication servers may be temporarily down. Check status.mojang.com.
If online-mode is true in server.properties, players must have legitimate Minecraft accounts.
If you recently changed online-mode, restart the server.

”You Are Not Whitelisted”

Solution: Add the player to the whitelist using /whitelist add <player> from the console, or disable the whitelist with /whitelist off.

Performance Issues

Low TPS (Lag)

Symptom: Players experience rubber-banding, delayed block breaking, or slow mob movement.

Diagnosis:

Install Spark if you have not already.
Run /spark profiler start from the console.
Wait 5-10 minutes during normal gameplay.
Run /spark profiler stop and review the generated report.

Common causes and fixes:

Too many entities: Reduce mob spawn limits in Paper config or use a mob management plugin.
View distance too high: Lower view-distance and simulation-distance in server.properties.
Heavy redstone machines: Identify and limit large redstone contraptions.
Chunk generation: Pre-generate chunks with Chunky.
Plugin overhead: Check Spark’s report for slow plugins and consider alternatives.

See our Performance Optimization guide for detailed tuning instructions.

High Memory Usage

Symptom: Server uses all available RAM and becomes slow or crashes.

Solutions:

Remove unused plugins and mods.
Reduce view-distance (each chunk loaded uses memory).
Set a world border to prevent infinite exploration.
Check for memory leaks using Spark’s memory analysis.
Upgrade to a plan with more RAM if your workload demands it.

Chunk Loading Lag

Symptom: Lag spikes when players explore new areas.

Solution: Pre-generate your world using the Chunky plugin. This generates chunks ahead of time so the server does not have to do it during gameplay. See the Performance Optimization guide for details.

Mod and Plugin Issues

Mod Conflict / Crash on Startup

Symptom: Server crashes with an error mentioning a specific mod.

Diagnosis:

Check the crash log in the crash-reports/ folder or the console output.
Look for the mod name in the error message.
Common causes:
- Missing dependency. Install the required library mod (listed on the mod’s download page).
- Version mismatch. The mod version does not match your Minecraft or mod loader version.
- Incompatible mods. Two mods may conflict with each other.

Resolution:

Remove the problematic mod.
Start the server to confirm it works without it.
Check the mod’s page for compatibility notes or updated versions.
If two mods conflict, check if either has a compatibility patch.

Plugin Not Loading

Symptom: A plugin does not appear in /plugins list.

Possible causes:

The plugin .jar file is not in the plugins folder.
The plugin does not support your server software version.
The plugin has a missing dependency. Check the console for error messages.
The plugin file may be corrupted. Re-download it.

”Unsupported API Version”

Symptom: Console shows a warning about an unsupported API version for a plugin.

Solution: The plugin was built for a different Minecraft version. Download the version of the plugin that matches your server’s Minecraft version.

World Issues

World Corruption

Symptom: Chunks are missing, terrain is glitched, or players lose inventory data.

Solutions:

Restore from a backup if available (check the Backups section in your dashboard).
If specific chunks are corrupted, delete the affected region files from world/region/. The server will regenerate those chunks (but player builds in those chunks will be lost).
Region files are named r.X.Z.mca. To find which file contains specific coordinates, divide the block coordinates by 512.

Cannot Load World After Version Change

Symptom: Server crashes or shows errors after upgrading or downgrading Minecraft version.

Solution:

Downgrading is not supported. Worlds that have been loaded in a newer version cannot reliably be loaded in an older version. Restore a backup from before the upgrade.
Upgrading is usually safe, but some major version jumps may require intermediate upgrades. If issues persist, restore a backup and try upgrading one major version at a time.

Crash Logs

When your server crashes, it generates a crash report. Here is how to find and use it:

Go to the File Manager in your dashboard.
Check the crash-reports/ folder for timestamped crash reports.
Also check logs/latest.log for the most recent console output.
Look for lines containing ERROR, FATAL, or Exception.
The crash report usually identifies the mod, plugin, or system that caused the crash.

When asking for help on Discord, always share the relevant crash log or error message.

Quick Checklist

Before contacting support, verify these basics:

Is the server running? Check the console in your dashboard.
Is the EULA accepted? Check eula.txt.
Are you using the correct address and port?
Does your client version match the server version?
Have you checked the console for error messages?
Have you checked crash-reports/ and logs/latest.log?
Have you restarted the server after making changes?

Still Need Help?

If you have worked through this guide and the issue persists, join our Discord and share:

A description of the problem.
What you have already tried.
Relevant error messages or crash logs from the console.
Your server software and Minecraft version.

Our support team will help you resolve the issue.