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Minecraft 20w49a
Java Edition 20w49a.png

Java Edition



Release date

December 2, 2020

Snapshot for



Client (.json)

Obfuscation maps


Protocol version

 dec: 1073741832
 hex: 40000008

Data version


20w49a is the fourth snapshot for Java Edition 1.17, released on December 2, 2020,[1] which adds sculk sensors, the dripstone caves biome, and the ability to expand the world height limit.



Sculk sensor
  • A new redstone component.
  • Detects vibrations, and emits a redstone signal.
  • Will emit a different strength if connected to a comparator, and the signal strength is based on the vibration's frequency.
  • Vibrations can be occluded using wool blocks.
  • Can only be obtained via the Creative inventory or commands such as /give.

World generation[]

Dripstone caves
  • A new underground biome.
  • Made up of primarily dripstone blocks and stone, with large clusters of dripstone blocks hanging from the ceiling, pointed dripstone on the floor and ceiling and many pools of water.
  • Does not generate naturally in normal worlds, and can only be generated using buffet worlds with "Dripstone caves" selected as the source biome or using custom world.


Death messages
  • Added death messages for being skewered by a falling stalactite:
    • "<player> was skewered by a falling stalactite"
    • "<player> was skewered by a falling stalactite whilst fighting <entity>"
  • New particle types: vibration and dust_color_transition


  • Added the dripstone_replaceable_blocks block tag.
    • Contains the base_stone_overworld block tag and dirt.
    • Used in dripstone generation to determine what dripstone can replace and what pointed dripstone can generate on.
  • Added the occludes_vibration_signals block tag.
    • Contains the wool block tag.
    • Blocks in this tag will prevent sculk sensors from hearing vibrations if the block is between the sculk sensor and the vibration.
  • Added new game_events tag type.
  • Added the ignore_vibrations_stepping_carefully game event tag.
    • Contains the step, falling, and shooting projectile events.
    • Game events in this tag will be ignored by sculk sensors if the source entity is sneaking.
  • Added the vibrations game event tag.
    • Contains every game event.
    • Game events in this tag will trigger sculk sensors.



Pointed Dripstone
  • When in a dimension with ultrawarm set to true, such as the Nether, downwards facing dripstone will create lava particles instead of water particles.




Absorption effect
  • The yellow absorption hearts will now stay yellow if the player has the Poison or Wither effects, instead of appearing empty.
  • Frozen hearts now appear in hardcore mode.
    • However, they appear the same as normal frozen hearts.


Custom dimensions
  • Added height and min_y variables to dimension types, allowing for the height limit to be increased in custom world settings.
    • The void now starts 64 blocks below min_y.
  • Removed the max-build-height server setting.


28 issues fixed
From released versions before 1.17
  • MC-18880 – The Absorption effect has no texture for poison/wither hearts (appears empty instead).
  • MC-46650 – When flying through blocks in spectator mode in F5, the camera zooms in and out a lot.
  • MC-201840 – Optional function tags sometimes don't run even when the tag exists.
From the 1.17 development versions
  • MC-203797 – Placing or removing a block over the void causes a DecoderException on servers.
  • MC-204314 – Double copper slabs only drop a single slab when mined.
  • MC-205043 – Absorption hearts appear broken when taking freezing damage.
  • MC-205096 – Hardcore hearts lose all color when player is taking freeze damage.
  • MC-205391 – Waxing cut copper does not prevent it from oxidising.
  • MC-205629 – Unused sign cache when rendering signs.
From the previous development version
  • MC-206553 – Pointed Dripstone creates water particles in the Nether.
  • MC-206563 – Pointed dripstone is not connected to the player's hand.
  • MC-206578 – Large pillars of stalactites don't fall when the block above is removed.
  • MC-206583 – Cauldrons below stalactites at least 2 blocks tall will not fill up.
  • MC-206591 – Setting any floating block to a pointed dripstone, causes the replaced block to drop as an item.
  • MC-206594 – Large stalactites falling occasionally do not drop all of their pointed dripstone items.
  • MC-206606 – Frustum stage of stalactites negates fall damage.
  • MC-206613 – Pointed Dripstone duplicates when the block it was attached to is removed.
  • MC-206615 – Pointed dripstone's hitbox can extend further than a block, causing nearby stalactites to not be able to fall.
  • MC-206642 – Stalactites destroy items they fall on, however stalagmites don't.
  • MC-206643 – When a dripstone's hitbox extends into the space of another block, the area that extends into said block cannot be targeted.
  • MC-206669 – Inconsistency between dripstone and non-mob entities.
  • MC-206682 – Floating dripstone tips are sometimes left behind from large dripstone pillars.
  • MC-206689 – Floating pointed dripstone top.
  • MC-206691 – Pointed dripstone replaces items with pointed dripstone items.
  • MC-206711 – Coding error at net.minecraft.world.entity.Entity.resetPos().
  • MC-206790 – Waterlogged dripstone does not update.
  • MC-206878 – Pointed dripstone attached to a piston is not removed as the piston extends.
  • MC-206961 – Flashing frozen hearts use the poisoned absorption heart texture.


Video made by Slicedlime:


  1. "Minecraft Snapshot 20w49a" – Minecraft.net, December 2, 2020