not letting me play

look at here  ---> MC-214806

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We're tracking this issue in MC-214806, so this ticket is being resolved and linked as a duplicate.

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ok thanks

https://www.minecraft.net/en-us/article/minecraft-snapshot-21w06a
you can keep playing on version 21w05a / b 🙂 Version 06 has new caves but does not have a system that connects the old world with the new caves

let me play my old worlds please 😞

can you please un disable it so i can play my old worlds please

If you aren't on the snapshot, you will be able to play them. To get a previous snapshot, go to the installations page (on the launcher). On the top right, make sure the box next to Snapshots is ticked. Then, click New in the top left. Click on where it says the version, then scroll to the desired version and click it. Then click Create.

Go back to the Play page, then click on the version in the bottom left. It should bring up all the versions, including latest version, latest snapshot, and whatever versions you have saved.

how long will this take to un disable my old worlds so i can play them?

For one, this is how it is and mojang will not disable it in this version unless you want the world to corrupt and lag out. You will need to wait until they implement a fix for terrain generation across versions. Nobody knows how long it will take.