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  1. Minecraft (Bedrock codebase)
  2. MCPE-151817

Incorrect cave biome data when upgrading world


    • Icon: Bug Bug
    • Resolution: Works As Intended
    • None
    • Preview, Preview, Preview, Preview, Preview, Preview, Preview, Preview, Preview, Preview, 1.18.2 Hotfix, 1.18.12 Hotfix, 1.19.0, 1.19.2 Hotfix, 1.19.10, Preview, 1.19.11 Hotfix, 1.19.20, 1.19.21 Hotfix, 1.19.30, 1.19.31 Hotfix, 1.19.40
    • Confirmed
    • Multiple
    • 795454

      When loading old chunks in an infinite world to new height limit, cave biomes below y=0 place features (dripstone, moss, etc.) but are overwritten by old surface biome.

      Steps to Reproduce:

      1. Upgrade world from before 1.18 Caves and Cliffs Part 2
      2. Go underneath old chunks and find a cave biome
      3. Wait for biome exclusive mobs to spawn, (axolotls or tropical fish in lush caves, drowned in dripstone caves under land biomes) killing other mobs to free mob cap.

      Observed Results:
      Axolotls, tropical fish, and drowned do not naturally spawn.

      Expected Results:
      The aforementioned mobs spawn in their appropriate biomes.

      Lush and dripstone caves under old chunks will appear to be added, however spawning rules and biome tinting are the same as surface biomes. Returning players may be confused when cave biomes in upgraded chunks behave like surface biomes, especially mushroom fields. Attached are two example locations in the provided 1.17 world that I tested upgrading on Windows 10 and iOS.

      As of 1.19.0: Newer cave biomes are not currently affected because only lush and dripstone caves can be found under old chunks. Feedback about what biomes should generate under old chunks is not within the scope of this bug report.

      1.17 Mcworld File

            ScreaperNinetyOne Jesse Young
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