Startup Issue with Minecraft - How can i Update AMP Java Version?

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 Podman
Application Minecraft
Module MinecraftModule
Running in Container Yes
Current State Failed

Problem Description

Issue

i install fresh AMP and with it Java. Now i get an error when i start Minecraft Java Server. It say the java version from AMP is lover than Minecraft. How can i Update AMP Java Version?

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

  • Install Java Minecraft Server
  • Configure Minecraft Server
  • Startup Minecraft server
2

I am getting the same error and AMP is not showing an update, for java, to the version that the newest version of Minecraft needs.

3

You can select the Java version in the settings, simply type “java version” into the top right search box.

4

The new verison of Minecraft, 26.x now requires Java 25, but that’s not appearing in the options you mentioned. The options are only 8, 11, 17, and 21.

Edit: This is a very easy fix. All you need to do is install Java 25 on your system using the following (if you’re using the “apt” package manager): sudo apt install openjdk-25-jdk

Afterwards, when you restart your server instance, it should pop up in the Java Versions setting.

As always, my information may not be accurate, or may not apply to you if you’re on a different distro or any other of the infinite reasons, so fact check it before running any commands.

5

I have done this and I still get the error

The container image (cubecoders/ampbase:java) has Java 21 pinned in manual mode via update-alternatives. That’s a CubeCoders decision baked into the image. Manual mode overrides auto-mode priority, so Java 25 (despite
having higher priority 2511 vs 2111) gets ignored unless explicitly set.

  1. AMP’s dropdown isn’t saving Java.JavaVersion for Java 25. We know the dropdown works correctly for Java 17 (Homestead01 has the full path saved). The fact that selecting Java 25 left the field empty suggests AMP’s
    Minecraft module either doesn’t recognize Java 25 as a valid option yet, or there’s a bug in the save path for versions above what the module was designed for.
  2. The image hasn’t kept pace with Minecraft’s Java requirements. Snapshots have required Java 25 since late 2025, but the cubecoders/ampbase:java default is still Java 21. CubeCoders should either update the default or
    ensure the dropdown reliably saves the selection.
6

I had the same problem but with a lot of switching it works. I dont know why but it seems like a bug…