Startup Issue with Minecraft - Issue starting server in version 26.1

Technical Support
, ,
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

I tried to update the server to version 26.1, but the server doesn’t start.

Reproduction Steps

  • Change version to 26.1
  • Update the server
  • Start the server
2

I get the same issue. I am trying to start a Fabric Server.
Error logs :
java.lang.RuntimeException: An exception occurred when launching the server!
at net.fabricmc.loader.impl.launch.server.FabricServerLauncher.main(FabricServerLauncher.java:71)
at net.fabricmc.installer.ServerLauncher.main(ServerLauncher.java:69)
Caused by: java.lang.RuntimeException: Error invoking MC server bundler: 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
at net.fabricmc.loader.impl.game.minecraft.BundlerProcessor.process(BundlerProcessor.java:102)
at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.locateGame(MinecraftGameProvider.java:212)
at net.fabricmc.loader.impl.launch.knot.Knot.createGameProvider(Knot.java:171)
at net.fabricmc.loader.impl.launch.knot.Knot.init(Knot.java:128)
at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:66)
at net.fabricmc.loader.impl.launch.knot.KnotServer.main(KnotServer.java:23)
at net.fabricmc.loader.impl.launch.server.FabricServerLauncher.main(FabricServerLauncher.java:69)
… 1 more
Caused by: 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
at java.base/java.lang.ClassLoader.defineClass1(Native Method)
at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1027)
at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:889)
at net.fabricmc.loader.impl.game.minecraft.BundlerProcessor$1.loadClass(BundlerProcessor.java:65)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:536)
at java.base/java.lang.Class.forName(Class.java:515)
at net.fabricmc.loader.impl.game.minecraft.BundlerProcessor.process(BundlerProcessor.java:85)
… 7 more

3

You need to select Java 25

4

In my case Java 25 was already selected, and I had to actually switch it to 21 then back to 25 before it worked.

I see tons of posts with the same issue so perhaps a pinned post with these fix instructions might be warranted.

  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.

Several users have confirmed these steps work:

2 Likes
5

It’s a bug that is being worked on

6

yep the swtiching helped me, thanks