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Minecraft 21w40a
Java Edition 21w40a.png

Java Edition



Release date

October 7, 2021

Snapshot for



Client (.json)

Obfuscation maps


Protocol version

 dec: 1073741868
 hex: 4000002C

Data version


21w40a is the fourth snapshot for Java Edition 1.18, released on October 7, 2021,[1] that merges and renames some biomes, tweaks world generation, mob spawning, and fixes bugs.



Copper Ore
  • Now drop 2-5 Raw Copper when mining instead of 2-3.


Cod, Salmon, Pufferfish, Tropical Fish, Squid, and Dolphins
  • Now only spawn in water from Y=50 to Y=64.
  • Additionally, tropical fishes now also spawn in lush caves at any height.
Glow Squids
  • Now only spawn in water blocks under Y=30.

World generation[]

  • The unused height variation sub-biomes have been removed from the code and merged with their default biome variants, as following:
  • Some biomes have been renamed:
  • Non-cave biomes (e.g. Savannas) no longer change with height.
  • Tweaked the relative size of some biomes, to match 1.17 a bit closer.
  • Increased the average size of most biomes.

Ore distribution changes.

Ore distribution
  • Copper Ore now generates between Y=-16 and Y=112, generating the most at Y=48, and increased the number of blobs.
  • Added more unexposed Diamonds.
  • Decreased minimum generation height of Emerald Ore from Y=32 to Y=-16, and increased the number of blobs.
    • This allows deepslate emerald ore to generate again.
  • Extra gold generates below Y=-48.
  • Decreased minimum generation height of the upper range of Iron Ore from Y=112 to Y=80, and increased the number of blobs.
  • Increased the amount of dungeons, especially below Y=0.
  • Now generates below Y=0, and increased the number of blobs.
  • Water lakes were removed, because Aquifers could provide local water levels.
Magma Blocks
  • Slightly increased the frequency of underwater magma.
  • Now slightly more spread out.
  • Bedrock layers generate dependent on the world seed now.


  • Due to the removal or merging of sub-biomes, the number of biomes required to visit for the "Adventuring Time" advancement has been reduced from 42 to 31, with the following biomes now being required:




46 issues fixed
From released versions before 1.18
  • MC-128770 – Woodland mansions still generate in dark forest hills.
  • MC-132306 – Snowy grass without snow near lakes in snowy biome.
  • MC-133582 – Dolphins try to catch up with boat on land.
  • MC-137140 – Llamas cannot spawn in shattered savanna plateau.
  • MC-137956 – Lakes still generate in superflat preset "Overworld" after removing its tag.
  • MC-138734 – Spawn point for seed 0, world type Buffet with badlands plateau biome is under surface, ⇒ player dies.
  • MC-138782 – Stranded dolphin tries to catch the boat on the water and stops beating.
  • MC-152966 – Increase in villages generating in versions after 1.10.
  • MC-169523 – As of 18w06a, the sand, clay and gravel blocks no longer generate around small lakes.
  • MC-177016 – Some lakes in frozen biomes generate unfrozen.
  • MC-190724 – Spawning in solid blocks in single biome "Badlands Plateau" world.
  • MC-197688 – Mountain edge never generates.
  • MC-200640 – Despite being a coastal biome, mushroom field shores don't have a warm/unique water color.
  • MC-200803 – Gravelly mountains+/modified gravelly mountains placed incorrectly in the biome selection.
  • MC-217906 – Large amounts of axolotls cause performance issues.
  • MC-224494 – Regular dirt can generate naturally on the surface near pools.
  • MC-225030 – Dungeons are extremely rare compared to in the past.
  • MC-225506 – Grass blocks can generate naturally in underground pools.
  • MC-225842 – Flowers can generate on large plants near lakes.
  • MC-225858 – Seeds and flowers appear in ponds.
  • MC-226000 – Pointed dripstone items in underground pools.
  • MC-226437 – Water lakes generating in snowy tundra's can sometimes contain dark spots.
  • MC-226682 – World can fail to render/load causing visual issues.
  • MC-227064 – Floating grass can still generate above water lakes.
  • MC-229365 – Large amounts of goats cause performance issues.
  • MC-231400 – Modified badlands plateau and mountain edge don't generate and gives out invalid biome data in single biome worlds.
  • MC-233661 – In some cases, sand blocks generating over lakes do not cause light updates, resulting in large dark spots.
  • MC-238006 – Emerald ore and infested blocks do not generate in snowy mountain biomes.
From the 1.18 development versions
  • MC-236609 – New mountain biomes use translations strings in biome selection.
  • MC-236614 – Adventuring Time advancement still accepts non generating biomes.
  • MC-236617 – Mountains and gravelly mountains use their 1.17.1 biome ID name.
  • MC-236632 – Banners without patterns do not render properly.
  • MC-236663 – Command blocks do not display command in their UI.
  • MC-236736 – No relief on treasure map or explorer maps.
  • MC-236894 – Foliage from specific biomes can generate in biomes they aren't meant for.
  • MC-236896 – Strange mini broken aquifer walls generating commonly on the surface.
  • MC-237490 – The bottom parts of aquifers aren't always surrounded by blocks which can occasionally cause them to spill into caves in ways that appear bizarre.
  • MC-237586 – Entities that die outside of simulation distance remain frozen in the death animation.
  • MC-237666 – Unused biomes still present in game files.
From the previous development version
  • MC-237925 – Opening world from 1.12.2 (or older) in latest snapshot regenerates random chunks.
  • MC-237933 – Sweet berries generate much too often.
  • MC-237950 – Cave vines can generate without tip because prioritize_tip option is negated.
  • MC-237951 – Cave vines can generate into water.
  • MC-237962 – Entities bob their head up and down when targeting towards the player.
  • MC-238104 – Blue orchid generation has decreased.
  • MC-238265version.json contains internal revision ID instead of game version ID.


Videos made by slicedlime:


  1. "Minecraft Snapshot 21w40a" – Minecraft.net, October 7, 2021