Startup Issue with Minecraft - My minecraft server wont start

Technical Support
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1

System Information

Field Value
Operating System Linux - Debian GNU/Linux 13 on x86_64
Product AMP ‘Deimos’ v2.7.0.0 (Mainline)
Virtualization Docker
Application Minecraft
Module MinecraftModule
Running in Container Yes
Current State Failed

Problem Description

Issue

Error: LinkageError occurred while loading main class net.minecraft.bundler.Main
	java.lang.UnsupportedClassVersionError: net/minecraft/bundler/Main has been compiled by a more recent version of the Java Runtime (class file version 69.0), this version of the Java Runtime only recognizes class file versions up to 65.0

Reproduction Steps

  • I treid to start the server
  • it gave me and error
  • I updated the server and set a backup schedule, but its still not working. What do i need to update or do?
2

I’m having the same issue after updating the server version to 26.1 from 21.11. I doubt it’s realated to the version numbering change, but it’s since the update that I can’t get a server started. I tried changing the Java version to 25, and the server will start, but I can’t connect to it.

3

I was able to get it working. Or at least get the server launching, haven’t tested if it actually connects and stuff.

  1. Update the minecraft instance itself
    • Either through Support and updates > “Update This Instance”…
    • Or in the list of instances click “Update Instance” on it.
  2. Inside the instance, go to Configuration > Minecraft > “Java and Memory” tab
  3. Under “Java Version”
    • If it’s set to “TEMURIN 25”, Switch it to 21, then back to 25, and restart the instance. That fixed it for me.
    • If it’s not already set to 25, try setting it to 25. If you don’t see that as an option try the “Scan for Java Installs” button.
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