Startup Issue with Minecraft - Upon starting fresh Minecraft Java instance it errors out

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

To reproduce just run any existing, or fresh Minecraft instance end encounter error
It seems like it’s just need a java update in it, updating and or recreating it does not do anything

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

  • Create new Minecraft instance
  • Go into instance and accept EULA
  • Get non working instance
2

Getting same issue, running docker containers, issue appears to be with the docker image as it only has java 21 installed, latest version is java 25, and that is what the installer is looking for.

3

Turns out, you can choose which version of java to use in Manage Instance => Configuration => Minecraft. If it is already set to java 25, change it to 21, and switch back to 25, it helped me

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