Affects Version/s: 1.15.2, 20w18a, 1.17.1
Fix Version/s: None
When optimizing old worlds (e.g. from Minecraft 1.0) their data is deleted.
Expected would be either, that
- optimizing includes upgrading (if necessary)
- optimizing older / unknown versions is not supported
- the warning text on the "Optimize World" screen is clearer and only shown when optimizing an older world, see MC-181274
- Create a world in Minecraft 1.0 or download test 1.0.zip
- Open the latest version and in the world selection, click "Edit"
- Select "Optimize world"
Note that the world now shows the current version as version on the world selection screen
- Open the word
You are spawned in the middle of the ocean (you should be in a swamp)