The “Minecraft” FAQ page goes into more detail about the account migration, which will either require a connection to your existing Microsoft account or the creation of a new one. For starters, it states that in no uncertain terms you will need to migrate over to a Microsoft account in order to continue playing after the cutoff date, after which your old Mojang account won’t be needed anymore. Logging in via a Microsoft account will also give you access to added security features, such as two-factor authentication.
All of your account information will be carried over, as well, so there’s no need to worry about losing your username, world, or other content. Mojang also says Microsoft account users that have access to the “Bedrock” version on any platform will be able to play both versions (“Bedrock” and Java Edition) from the same Microsoft account.
It also clarifies that account migration won’t change any of the Java Edition’s limitations, so if you’re hoping to use your updated account and this version of the game to play with friends on other platforms, it’s not going to happen — Java Edition players can still only play with other Java Edition players.
