MC-VECTORWiki

Common Errors

Solutions to the most frequent errors when running a Minecraft server with MC-Vector.

This page covers common errors you may encounter when creating or running a Minecraft server with MC-Vector.

Server Fails to Start

java.lang.OutOfMemoryError

Cause: The server does not have enough memory allocated.

Fix: In MC-Vector, go to the server's Settings tab and increase the Memory value. Make sure your machine has enough free RAM.

Address already in use

Cause: Another process is already using the port (default 25565).

Fix:

  1. Check if another Minecraft server is running on the same port.
  2. Go to the Properties tab in MC-Vector and change server-port to a different value (e.g. 25566).

EULA not accepted

Cause: When creating a server manually or if the automatic EULA acceptance fails, the server won't start.

Fix: Open the Files tab, find eula.txt, and change eula=false to eula=true, then save.

Note: MC-Vector automatically accepts the EULA when creating a server through the app.

Connection Issues

Connection refused

Cause: The server is not running, or a firewall is blocking the port.

Fix:

  1. Make sure the server status shows Online in MC-Vector.
  2. Check that your firewall allows inbound connections on the server port.
  3. If you want to play with friends over the internet, see the ngrok Tunnel guide instead of configuring manual port forwarding.

Plugin / Mod Errors

UnsupportedClassVersionError

Cause: The plugin or mod was compiled for a newer version of Java than what is currently running.

Fix: Open the Java Manager in MC-Vector and switch to a newer Java version (e.g. Java 21), then restart the server.

Server crashes after installing a plugin/mod

Fix:

  1. Go to the Files tab and navigate to the plugins/ or mods/ folder.
  2. Remove the newly added .jar file.
  3. Restart the server and check the logs/latest.log for the specific error message.