Minecraft: Java Edition Snapshot 21w15a released alongside 'Caves and Cliffs Update' delay announcement

Minecraft Caves and Cliffs Update Image
Minecraft Caves and Cliffs Update Image (Image credit: Mojang Studios | Twitter)

What you need to know

  • Minecraft's 'Caves and Cliffs Update' is now being split into two parts, with the second part delayed until later this year.
  • The latest Minecraft: Java Edition snapshot is rolling out in response to the 'Caves and Cliffs Update' delay.
  • Many features that are now coming in the second update this winter are being shut off in Snapshot 21w15a.
  • Testers can restore these features and keep testing them by installing a new experimental datapack.

Minecraft is having a big news day, but it's not exactly a happy occasion. The ambitious and hotly-anticipated Caves and Cliffs Update for Minecraft has been split into two parts and delayed, with Mojang Studios citing the technical complexities of the update and their need to preserve the health of their teams. In response to this announcement, Minecraft: Java Edition Snapshot 21w15a is now rolling out to PC Minecraft testers with an interesting batch of changes for the Caves and Cliffs Update.

While there are new features and changes in the latest Minecraft: Java Edition snapshot, many of the features that have been tested in previous snapshots are actually being removed. Most of the world generation changes from the Caves and Cliffs Update have been delayed and aren't releasing until Winter 2021, so these features are being shut off in Snapshot 21w15a.

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The world generation features being removed in Minecraft: Java Edition Snapshot 21w15a include:

  • World height has been switched back to the 1.16 levels
  • Noise caves and aquifers have been switched off
  • Cave and ravine carvers have been returned to their old settings
  • Crack carvers have been switched off
  • Ore distribution has been returned to the 1.16 setup
  • Copper now generates between the bottom of the world and height 192, being most common around height 96
  • Tuff now generates in blobs between heights 0 and 16
  • Worlds created in snapshot 21w05b or any earlier version can now once again be opened
  • Worlds created in any version between snapshot 21w06a and 21w14a can no longer be opened

If players want to continue testing these experimental features, which now aren't arriving until much later this year, they still can! Mojang Studios is introducing a new datapack that creates an experimental custom world in Minecraft, where the removed snapshot features will still be active.

To test the removed Caves and Cliffs Update features in Minecraft, you'll need to follow these steps:

  1. Download the new datapack from the Mojang Studios website
  2. Launch the game, go to the "Create New World" screen, and click the "Data Packs" button
  3. Drag the downloaded zip file onto the Minecraft window
  4. The game will ask you if you want to add the data pack – click "Yes"
  5. Click the play arrow on the data pack that just appeared in the list – this will move it to the list on the right-hand side of the screen
  6. Click the "Done" button and continue creating your world as normal

Beyond those changes, Snapshot 21w15a actually does include new features that should be arriving in the first half of the Caves and Cliffs Update in Summer 2021.

The full changelog for Minecraft: Java Edition Snapshot 21w15a includes:

New features

  • Goats will ram anything that moves… and also armor stands


Source: Mojang Studios (Image credit: Source: Mojang Studios)
  • A crinkly, crunchy sound now plays when Bone Meal is used
  • Reordered some blocks in the Building Blocks Tab in Creative Menu
  • Goats will avoid walking on Powder Snow
  • Creepers know won't dare mess with Goats
  • The main menu background has been updated
  • Tweaked the textures of raw ore items
  • Just like other ore materials, you can craft a compact version with raw ore items in order to save inventory space

Building blocks tab

  • All ores have been reordered to be in the same location in the creative inventory
  • Compact forms of raw and refined underground materials have been reordered

Technical changes

  • Added the Marker entity
  • Added /debug function
  • selector and nbt chat components can now configure separators between elements
  • Servers can now customize a message to display when prompting players about custom resource packs


  • Markers are a new type of entity meant for custom use cases like map making and data packs
  • Only exist on the server side, are never sent to clients
  • Do not do any updates of their own
  • Have a data compound field that can contain any data

Debug function

  • New debug subcommand executes command with same syntax as function
  • Every executed command, message (even if it would be normally invisible), result or error is stored to file
  • Cannot be run from inside functions

Chat component separators

  • Components that print lists of names, like selector or nbt can now override separator (, by default) with separator element

Custom server resource packs

  • When require-resource-pack is used in server.properties, there's now an option for servers to add a custom message
  • A dedicated server can configure additional message to be shown on resource pack prompt (resource-pack-prompt in server.properties, expects chat component syntax, can contain multiple lines)

Bug fixes

  • A geode configured_feature causes a crash when use_alternate_layer0_chance is used with no entries in inner_placements
  • Summoning Glow Lichen using /setblock doesn't place any lichen but creates light until the block is updated
  • Glow Lichen doesn't render when being held by an Enderman
  • Deepslate uses the same color as stone on maps
  • Stone still generates around lava pools at low levels
  • Feature placement - java.lang.IllegalArgumentException: bound must be positive
  • Cracked deepslate bricks & tiles are in the incorrect position in the creative inventory
  • Infested deepslate makes the old "stone" sounds
  • Deepslate emerald ore is separated from other deepslate ores in the creative inventory
  • Deepslate coal ore doesn't drop experience
  • Copper ore and deepslate copper ore have inconsistent textures
  • Deepslate gold ore has an inconsistent pixel
  • Water splash potions don't give the axolotl 1.5 minutes of moisture
  • Lava fog repeatedly fails to render each block at certain y-levels
  • Blindness doesn't render correctly
  • Beacon beam fog is incorrectly computed
  • Goats don't attack
  • Nether Gold Ore is no longer smeltable
Zachary Boddy
Staff Writer

Zachary Boddy (They / Them) is a Staff Writer for Windows Central, primarily focused on covering the latest news in tech and gaming, the best Xbox and PC games, and the most interesting Windows and Xbox hardware. They have been gaming and writing for most of their life starting with the original Xbox, and started out as a freelancer for Windows Central and its sister sites in 2019. Now a full-fledged Staff Writer, Zachary has expanded from only writing about all things Minecraft to covering practically everything on which Windows Central is an expert, especially when it comes to Microsoft. You can find Zachary on Twitter @BoddyZachary.