Update Failure with Minecraft - Attemp to start Minecraft 1.21 ... but keeps starting 1.20.1

System Information

Field Value
Operating System Linux - Debian GNU/Linux 12 on x86_64
Product AMP ‘Callisto’ v2.5.1.0 (Mainline)
Virtualization Docker
Application Minecraft
Module MinecraftModule
Running in Container Yes
Current State Ready

Problem Description


I have tried numerious times to update to 1.21 … shows update in console log history, but when clicking start, console shows 1.20.1 starting. Version command come back showing 52 versions behind. Have attempted to force the start of 1.21, no joy. I have renamed the older jar files (1.20.1-1.20.5), but when restarting, it re-maikes all of the files and starts 1.20.1 again.

Reproduction Steps

  • Shut down Server
  • Click update — update runs showing 1.21 and make new jar file in instance directory
  • Click start — shows in console starting 1.20.1
  • Shutdown - and chance to force 1.21
  • restart — still 1.20.1

Running current java: TEMURIN 21 (jdk) [System Default]

How did you attempt to ‘force’ it to start in 1.21?
Make sure you are scanning and selecting the new .jar file when it is created:

Select the Minecraft Instance → Configuration → Minecraft → Server and Startup →

(Select the Proper Server Type, and if you have it selected already just hit Download/Update)

Scroll down on this page and you will see the ‘Server JAR’ box with a dropdown and a Scan Button → Select Scan for new JARs after downloading the latest update

Give it a moment then click the drop down and look for the 1.21 jar.

Start the Server and see if the issue persists.

Let me know if you want to do a quick discord call and I can guide/troubleshoot with you that way too.



Ok … see where I missed the jar file. Set it and the server started on 1.21. New issue is that all the players lost their inventories both on the bar and all inventories in chests. Is there a way to get those back?

You can easily recover that data if you had any backups.
Otherwise, probably not.