Minecraft Java no longer working after account merge :(

Hi there! I'm Rostom, an Independent Advisor. I will be glad to help you here. I understand how that feels. No worries, we will do our best now to get this sorted out.

Have you already tried resetting your Minecraft Launcher, Microsoft Store, and Xbox app?

You can do that by going to Start > Settings > Apps > Apps & features. Find those apps and click on Advanced option to reset them.

Bonjour and Hello!

I hope it's okay if I reply this in English, you can maybe use a translator.

Did you try the Merge feature on MineCraft?
It's best to read further information about it: Merging Minecraft Accounts.

Also, by reading further:
What will happen to my Mojang account after I migrate to a Microsoft account?

You won't need it anymore! After migrating you'll use your Microsoft account to log in to the Minecraft Launcher to play the game and log in to minecraft.net to manage your settings.

So perhaps try the Microsoft account.

Hope this works!
Sparrow

Hi ghost_hotline

Recently, Microsoft started to integrate Minecraft Java accounts with Microsoft accounts. Could you have merged the wrong account at some point or signed in with the wrong account?

More details on usernames and Gamertags can be found here:

Minecraft: Java Edition Username VS Gamertag FAQ – Home

No access to Minecraft: Java Edition after migrating account to Microsoft

I tried everything nothing works

I have the same problem. Purchased Java version a long time ago, and Xbox more recently. Now I can't migrate my mature Java account. They need to implement a mechanism by which accounts may be merged. Completely insecure and unacceptable to ask users to create new Microsoft accounts just to play Minecraft.