Minecraft server won't start or crashes on startup

If your Minecraft server goes offline a few seconds after you press Start, or never finishes loading, the reason is almost always written in the Console. Find that message first, then use the matching fix below. The causes are listed from most to least common.

Step 1: Find the error message

1. Open your server in the Game Panel and go to Console.

2. Press Start and watch the output. When it stops, scroll up to the first line that says ERROR, Exception or Caused by. The first error is usually the real cause; later errors are often side effects.

3. If the text scrolls away too fast, open Files → logs → latest.log. If the server crashed, also look in the crash-reports folder. Our guide on reading logs and crash reports explains what to look for.

Wrong Java version

You will see java.lang.UnsupportedClassVersionError or a line like "has been compiled by a more recent version of the Java Runtime". When you install software from the Versions tab, the panel picks the correct Java for you (a fresh Paper 26.3 server runs on Java 25 automatically). So this error usually appears only after you uploaded your own server jar or changed the Docker Image by hand in Startup. Each Minecraft version needs a certain Java version:

The easiest fix is to reinstall your software and version from the Versions tab, which sets the right Java again. If you run a custom jar, stop the server, open Startup → Docker Image, pick the matching Java (the list goes from Java 8 to Java 25) and start again. Full steps: How to change your server's Java version.

EULA not accepted

The first time you press Start on a new server, a popup called Accept Minecraft® EULA appears. Click I ACCEPT and the server boots. If you clicked CANCEL, the console says "You need to agree to the EULA in order to run the server". Press Start again and accept, or open Files, edit eula.txt, change eula=false to eula=true, save and start the server.

A plugin or mod is crashing the server

The error or crash report names a plugin or mod, or shows a package name such as com.someplugin. Common cases:

• Outdated plugin or mod that does not support your Minecraft version. Update it or remove it.

• Missing dependency, for example a mod that needs a library mod such as Fabric API. The log usually says which one is missing.

• Client-only mod on the server. Messages like Attempted to load class net/minecraft/client/... or invalid dist DEDICATED_SERVER mean a mod made only for players (minimaps, shaders, menus) is in the server's mods folder. Remove it from the server.

• Wrong type of add-on: plugins only work on Paper, Purpur or Spigot; mods only work on Fabric, Forge or NeoForge.

Not sure which file is guilty? Move half of your plugins or mods into a new folder such as disabled in Files and start the server. Keep halving until you find the one that crashes it.

Disk is full

Errors with "No space left on device", or a server that cannot save, mean your disk is full. Check the Disk usage at the top of the panel. Delete old log files, unused worlds and old archives, or upgrade your plan for more NVMe space.

Other common messages

• OutOfMemoryError: see OutOfMemoryError: Java heap space.

• FAILED TO BIND TO PORT: see Failed to bind to port.

• Unable to access jarfile or Invalid or corrupt jarfile: the server jar is missing or damaged. Reinstall the same software and version from the Versions tab without ticking Wipe Server Files. If you uploaded or renamed the jar yourself, make sure the name matches the SERVER JAR FILE variable in the Startup tab.

• "Server attempted to load chunk saved with newer version of minecraft": the world was opened on a newer Minecraft version. Going back to an older version is not supported. Switch back to the newer version in Versions, or restore a backup from before the update in Backups.

• Exception in server tick loop: see Exception in server tick loop.

The server starts, but you can't join

If the console shows Done but you are kicked with "You are not whitelisted on this server", the server is fine. New servers have the whitelist turned on (white-list=true). Type whitelist add YourName in the Console or add yourself in the Players tab, then join again. See Whitelist, OP and ban players.

Frequently asked questions

Still stuck? Open a ticket with your server name and the error lines from latest.log.