Minecraft Update 1.18 Snapshot 21w38a Patch Notes Today

Here are the patch notes of Minecraft Update 1.18 Snapshot 21w38a.

September 22, 2021

Minecraft’s next Snapshot is all set to release very soon and fans are eagerly waiting for its arrival.

  • MORE: Minecraft 1.18 Update Experimental Snapshot 7 Patch Notes Today

After a number of experimental snapshots consisting of pre-release candidates, we have finally started receiving normal snapshots for the upcoming Minecraft update. Here is all you need to know about the second snapshot that the game is all set to get.

Minecraft Update 1.18 Snapshot 21w38a Patch Notes


  • Sprinting is no longer reduced to walking when gently brushing your sleeve against a wall
  • Fixes for the distribution of ores


  • Copper ore generates up to y 95 (as originally designed)
  • Increased the amount of copper
  • Lapis lazuli generates in blobs, like other ores (instead of spread out)


  • Previously, any collision with a block would reduce sprinting to walking. Now, for very minor angles of collision with a block, players retain their sprint. For larger angles of collision, the old behavior is retained.


  • A new setting has been added: “Simulation distance”
  • Maximum amount of background threads increased
  • Added telemetry for world loading


  • Entities will not be updated outside of simulation distance.
  • Allows higher render distance with less CPU load.
  • A new slider in video settings on the client.
  • A new simulation-distance property in dedicated server properties.
  • We will continue working on it with a goal of simulation distance also affecting block and fluid ticking.


Various background tasks including worldgen are executed on a background thread pool. Its size equals the amount of available CPU threads minus one, but there was an upper limit of 7. Now this upper limit is 255. This should help higher-end machines with world-gen performance.

The upper limit can be overridden by Java system property, for example when running multiple servers on a single machine.


In this release, we are re-introducing diagnostic tracking, which was part of Minecraft: Java Edition until 2018. We are bringing it back to better understand our players and to improve their experience. Specifically, we hope to ensure stronger performance for the extremely heavy world generation in the second part of the Caves & Cliffs update later this year.

In practice, this can mean identifying technical pain points in the game, like how less powerful hardware performs in high-complexity terrain. This information will also help us prioritize various aspects of development, balance game features (by learning, for instance, that the goats are pushing every single player off the cliffs) and lend new Minecrafters a helping hand (after realizing that many of them get stuck at the same points). All data is treated according to GDPR and CCPA best practices and is used to develop a better-performing and generally more enjoyable Minecraft: Java Edition.

At this point the only implemented event is world load.


  • Sent when loading singleplayer world or connecting to multiplayer server
  • Contains following information:
    • launcher identifier
    • user identitifer (XUID)
    • client session id (changes on restart)
    • world session id (changes per world load, to be reused for later events)
    • game version
    • operating system name and version
    • Java runtime version
    • if client or server is modded (same information as on crash logs)
    • server type (single player, Realms or other)
    • game mode


  • MC-44055 – Game fails to switch the audio output from one device to another after the game has started (from title screen)
  • MC-236611 – No sound for using shears on weeping, twisting, cave vines or kelp
  • MC-236618 – Strongholds don’t generate in 21w37a
  • MC-236621 – Liquids sometimes do not propagate
  • MC-236633 – Random light level of 0 in sky
  • MC-236656 – Crash when changing render distance / java.lang.ArrayIndexOutOfBoundsException: Index 28084 out of bounds for length 26136
  • MC-236665 – Memory leak in 21w37a
  • MC-236698 – Big Spruce Trees don’t generate in Groves
  • MC-236711 – Starting and stopping JFR profiling multiple times within the same minute overwrites previous JFR results saved during that minute
  • MC-236718 – Dripstone caves generate above the ground
  • MC-236795 – Cannot start with alternate JVM due to JFR requirement
  • MC-236873 – Problems with JFR event metadata
  • MC-236967 – Too many aquifers on biome surfaces at Y=63 and below
  • MC-237109 – Aquifers often generate with harsh straight borders
Md Armughanuddin

Md (He/Him) is the Head of Content- India for DualShockers. He is pursuing Computer Science Engineering and is really passionate about gaming and technology. You can find him cracking complex coding problems during the day, and covering the latest happenings in the industry at night.

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