Minecraft 1.21.5 pre-release 1 and 2 patch notes: All you need to know

With the first Minecraft Live of 2025 less than two weeks away, Mojang Studios has started adding final touches to the upcoming spring game drop. The Minecraft 1.21.5 update was unveiled in the first week of January this year and has since gone on to reveal new features, ranging from exciting new blocks to brilliant mob variants.

The update is finally close to its official release, as Mojang has released the first pre-release for version 1.21.5.

For the uninitiated, pre-releases are versions released after developers have implemented fresh features and changes for the next update. These preview releases are mostly filled with bug fixes and often include technical changes.

Minecraft 1.21.5 pre-release 1 is no different, as it has made technical changes to certain commands and the network protocol, along with many bug fixes related to TNT, excessive VRAM usage, and more.

Without further ado, let's go through the patch notes for the latest Minecraft 1.21.5 pre-release 1.

Update: Second pre-release is now out with a few more bug fixes.

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Minecraft 1.21.5 pre-release 2 patch notes

Technical Changes

• The Data Pack version is now 71 since this was missed in pre-release 1

Fixed bugs in Minecraft 1.21.5 pre-release 2

• MC-280482 - Main menu is totally broken when using Mesa 25.0
• MC-296644 - Game crashes while rendering section / java.lang.NullPointerException: Cannot read field "b" because "$$3" is null
• Additional crash fixes

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Minecraft 1.21.5 pre-release 1 patch notes

Changes

• Added Spawn Eggs textures for programmer art texture pack

Technical Changes

• The Resource Pack version is now 55
• Arguments in commands that accept inline values like loot tables, predicates, modifiers, data components, formatted text (\loot, \give, \tellraw, \execute if predicate, data components in \execute if items, etc.) have been reverted to accept numbers in place of booleans

"Developer's Note: The original change happened because we moved away from using NBT as an intermediate format for parsing those values, which meant that booleans were separated from numbers (similar to handling in JSON). We've decided to temporarily revert that, since some functionality can't be achieved yet without using storage and macro functions. However, once that missing functionality is added (and data can be transferred without being converted to and from text), legacy boolean handling will be removed once again."

Network Protocol

• The clientbound player_chat packet now contains an index increasing for every message sent to the client
• The index starts at 0 when logging in (or is reset by configuration phase and the login packet)
• For every message, the server should increment this value by 1
• If this value updates in an unexpected way, the client will disconnect
• As the protocol requires that every chat packet reaches the client in produced order, the goal is to enable faster detection of missed/reordered chat messages for custom server developers
• The serverbound chat and chat_command_signed packets now contain a checksum byte along with the 'last seen' update
• This is a simple hash of the 'last seen' signatures which should be reconstructed by the server, allowing quicker detection of desynchronized state
• This can be passed as 0 to disable the check, for compatibility with protocol translation

Resource Pack Version 47 through 55

• Tweaked Leaf Litter block models

Fixed bugs in Minecraft 1.21.5 Pre-Release 1

• MC-170134 - Minecraft uses several times more VRAM than needed after exploring terrain for a while
• MC-279350 - Leaf litter multipart model system is unoptimized, causing render lag
• MC-280141 - Baby farm animals from spawn eggs with a variant differing from the parent flash the wrong variant initially
• MC-280241 - Cold Cows have improperly mirrored and incorrectly aligned ear textures
• MC-280249 - Spawn eggs don't use their old textures with the Programmer Art resource pack enabled
• MC-280278 - Sheep wool uses 1.14 texture with Programmer Art resource pack enabled
• MC-280326 - When teleporting across dimensions an error is often thrown
• MC-280361 - When a fallen tree replaces the bottom half of tall vegetation, the top part of the vegetation still generates
• MC-280474 - TNT minecarts explode regardless of tntExplodes gamerule
• MC-280477 - TNT still explodes when summoned or dispensed while tntExplodes gamerule is false
• MC-280479 - TNT is completely deleted when attempting to ignite it using redstone pulses when the “tntExplodes” gamerule is disabled
• MC-280480 - No flint and steel clicking sound when attempting to ignite TNT with a flint and steel when the "tntExplodes" gamerule is disabled
• MC-280493 - If the tntExplodes game rule is changed to false while primed TNT already exists in the world, the primed TNT explodes as normal
• MC-280501 - The "Fire extinguishes" sound plays every game tick while on fire in rain
• MC-280520 - ItemDropChance on an item frame is not serialized when there is no item anymore, leading to inconsistencies

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Minecraft 1.21.5 pre-release 1 is a signal from the developers to fans, asking them to prepare for the upcoming spring drop update. This comes as no surprise, as Minecraft Live 2025 is set to take place on March 22. In the last livestream event, Mojang released the Bundles of Bravery update just a few weeks after the stream. Fans can expect a similar timeline for the Spring Drop 2025.