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  1. Minecraft: Java Edition
  2. MC-240570

Biomes in old chunks are not copied to new caves below Y=0 when chunks are extended


    • Icon: Bug Bug
    • Resolution: Fixed
    • 1.18 Pre-release 2
    • 21w44a
    • None
    • Confirmed
    • Datafixer, World generation
    • Important

      If an old world is upgraded, the biomes in the old chunks are not copied when the new caves are generated. The biomes are copied above Y=256 but not below Y=0.

      NOTE: This was originally reported as an incorrect debug screen, until I looked at the world save and figured out what was really going on.

      Steps to reproduce:
      1. Create a new world in an older version. (I used 1.6.4 and 1.15.2 and seed 1 for both.)
      2. Save this world.
      3. Load this world in the latest snapshot (21w44a).
      4. Go into spectator mode and inspect the biomes in upgraded old chunks -> Below Y=0, the biomes are not consistent with the biomes at higher y levels.

            grum [Mojang] Grum (Erik Broes)
            bdm68 bdm68
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