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Minecraft 21w17a
Java Edition 21w17a.png

Java Edition



Release date

April 28, 2021

Snapshot for



Client (.json)
Data pack[note 1]

Obfuscation maps


Protocol version

 dec: 1073741849
 hex: 40000019

Data version


21w17a is the nineteenth snapshot for Java Edition 1.17, released on April 28, 2021,[1] which tweaks the raw metal block textures, adds noodle caves and fixes bugs.





Changes have been made to the official Caves & Cliffs world generation preview datapack, which gives early access to the world generation coming in Java Edition 1.18.

Noodle caves
  • A thinner, squigglier, tighter variant of spaghetti caves.
  • These are an improved version of the mesh caves announced around Minecraft Live.



Amethyst cluster
  • Removed unused 'lit' blockstate.
Block of Raw Metal
Copper and Deepslate Copper Ore
  • Now drops 2–3 raw copper when mined, or more when using a tool enchanted with Fortune.
Copper block
Deepslate coal ore and deepslate copper ore
  • Now can spawn naturally.
Hanging roots
Small dripleaf



World Generation[]



Recipe Book
  • The recipe for crafting mossy stone bricks from moss blocks or vines is now unlocked with moss blocks or vines, respectively, rather than mossy cobblestone.
  • The recipes for dyed candles are now grouped.
  • The recipes for smelting and blasting ores into their respective materials are now grouped by ore type (i.e. smelting coal ore and deepslate coal ore are grouped).
    • For iron, gold, and copper, the recipes for smelting and blasting their raw materials into ingots are also grouped with their respective ore smelting and blasting recipes.
  • The recipes for crafting copper ingots from copper blocks and waxed copper blocks are no longer grouped.[3]
  • The recipes for mossy stone bricks are now grouped, as are the recipes for mossy cobblestone.
  • Many of the waxed copper block recipes were grouped together.


  • Added the wither to the freeze_immune_entity_types entity type tag.


Changes have been made to the official Caves & Cliffs world generation preview datapack, which gives early access to the world generation coming in Java Edition 1.18.

Ore veins
  • Snake veins are now slightly rarer and slightly smaller.
  • Ores are clumpier and less evenly distributed.
  • Now have a chance to rarely contain raw metal blocks.


21 issues fixed
From released versions before 1.17
  • MC-170443 – Banner copying recipe ignores existence of other items in crafting grid.
  • MC-187664 – World border uses float to determine its size, making some border sizes inaccessible, and cannot be set to 30 million or beyond.
  • MC-197805 – Minecraft crashes every time when attempt to craft something (caused by BungeeCord or Paper).
  • MC-201269 – Constantly teleporting player to a phantom crashes the game/kicks the player.
From the 1.17 development versions
  • MC-203570 – Candles aren't grouped in the recipe book.
  • MC-203745 – Repeated teleport between dimensions causes the entity to duplicate on the client.
  • MC-204031 – Waxed Cut Copper (any level of weathered) have two separate recipes in the recipe book.
  • MC-214187 – Void platform generates multiple times.
  • MC-214735 – Horse disappears when dying while riding it and reloading the world while it's unloaded.
  • MC-214838 – Big dripleaf stem remains after breaking a stem or leaf above it.
  • MC-214865 – Floating islands world type generates extreme terrain.
  • MC-219155 – Fishing line only starts on half distance between the fishing rod and bobber (Apple M1 only).
  • MC-219840 – You cannot unlock the recipe for Mossy Stone Bricks.
  • MC-219842 – Recipes for mossy cobblestone and mossy stone bricks aren't grouped.
  • MC-220033 – (Parity issue) Hanging Roots can't be waterlogged.
  • MC-221560 – Copper/Coal Ore in Deepslate Patches aren't Deepslate Ores.
  • MC-222008 – Empty/missing template pool error grammar mistake.
  • MC-222107 – sounds/mob/goat/pre_ram3.ogg missing from entity.goat.prepare_ram sound event.
  • MC-222520 – Raw and Ore smelting previews aren't grouped together.
  • MC-223055 – Amethyst buds and cluster have an unused blockstate.
  • MC-223792 – Shrinking world border with center past x/z = 29999983 crashes the game.


Videos made by slicedlime:


  • This is the first snapshot to implement a semi-revealed feature, namely mesh caves (renamed to noodle caves in this update).


  1. "Minecraft Snapshot 21w17a" – Minecraft.net, April 28, 2021
  2. MC-220033 – "(Parity issue) Hanging Roots can't be waterlogged" – resolved as "Fixed"
  3. MC-224389 – resolved as "Fixed"


  1. Re-enables features set to release for 1.18.