In 2020, the developers announced a major update to Minecraft: Java Edition. Players will soon have to switch from a Mojang account to an Microsoft account to continue playing. Jasonotto.net ' in relative terms, as we still haven't actually hit the deadline but the developers have just confirmed the date and sent out the final request for account migration.
As of March 10, you will no longer be able play Minecraft: Java Edition with an account with a Mojang account. The developers are encouraging all users to switch to Microsoft accounts for "improved security and player security" and are entice players to switch with the promise of free Minecraft capes.
Here are all the details about how to migrate your account. Java Edition will continue to be supported in the normal way following the change and will continue be a distinct entity from Bedrock. This is a purely unification of the accounts systems. You can keep your old username - all you need is an Xbox gamertag.