Java Edition 25w16a

25w16a is the second snapshot for Java Edition 1.21.6, released on April 15, 2025,^[1] which adds more functionality and improvements to leads, technical changes to shaders, and fixes bugs.

POI

• Added the test_instance POI.

Firework rocket

• While gliding, using a firework rocket will only be used as a boost even if placed on a block.

Lead

• Leashed leads are now rendered twice as thick, to match Bedrock Edition.
• Leads can now be used to leash two mobs together.
  • Sneak-interact on any mob while holding a bunch of leashed mobs will leash these mobs to the interacted entity.
  • It's not possible to leash anything to itself.
• If the re-leashing an entity would result in immediate leash snapping due to distance, the re-leashing would not happen.
• Leads can be snipped from an entity when interacting them with shears, which consumes their durability.
  • This applies to its own leash connection as well as all entities attached to it.
  • Dispensers can now snip leashes from entities in front of them when they are equipped with shears; this also consumes their durability.
• The leash mechanics were improved, with reworked leash physics, allowing for more stable leash connection, especially when leashed entities are not on ground.
  • When dragged on the leash, leashed objects will now orient themselves towards the leasher.
  • Using a firework rocket when flying with leashed entities will now break the leash connections.
• When leashing an already leashed mob, the current leash will now snap and a player will re-leash the object to the player.
  • It's not possible to steal leashed entities from other players.
• The interactions with a leash knot and fence blocks have changed:
  • When interacting with a leash knot or a fence, if there are any player-leashed entities in range of the leash knot, they will be re-leashed to the leash knot or a fence.
  • In case of attaching of mobs fails due to distance or there is nothing to attach, the player will now transfer all fence leashed entities to itself.
  • If there is nothing left attached to the leash knot, it disappears.
  • Sneak-interact can only result in attaching of the player mobs to the fence.
  • Interacting with shears or punching the leash knot will result in all current connections broken.
• Boats, as well as large mobs that can be leashed but cannot fit in a boat (horses, donkeys, mules, camels and sniffers), can now be leashed in a special 4-leash configuration to the happy ghast.
  • Happy ghast will also present a custom layer when it's leashing something using a quad connection.
  • Leashes in quad connection are now rendered without slack.
• Leash snapping distance has been changed from 10 to 12 blocks.
  • The distance between centers of entities bounding boxes, rather than their feet is used to determine the distance between two leashed entities.
  • Happy ghast leash is now longer - with free roaming distance of 10 blocks and leash snapping at 16 blocks.

Block models

• Block model rotations are no longer limited to multiplies of 22.5.
  • elements[].rotation.angle value in block models is no longer limited to multiplies of 22.5 degrees and can now be any angle from -45 to +45.

Clouds

• Clouds now exist all the way to the horizon.

Data component format

• painting/variant
  • No longer accepts inline variants.

Data pack

• The pack format version is now 73.

Resource pack

• The pack format version is now 57.
• All core shader uniforms are now uniform blocks.
• The cloud texture (clouds.png) can no longer be colored.

Shaders

• All built-in uniforms are now uniform blocks instead of opaque loose uniforms.
• Custom uniforms provided to post-process shaders are now uniform blocks.
• Uniform definitions inside JSON files are now per-block.
• Post-process effect definitions
  • Entries in the targets map have been expanded to support new properties.
    • New optional boolean field: persistent
      • Default: false
      • If true, this render target will be persistent across frames.
      • The contents of the target will be cleared when the screen is resized.
    • New optional field: clear_color
      • Default: [0, 0, 0, 0]
      • Format: integer ARGB value, or float array in order [R, G, B, A]
      • When this target is created or cleared, it will be filled with this color.
  • The uniforms values is now a list-per-block, instead of a global list.
    • e.g. uniforms: { "UniformBlockName": [ { "type": "vec2", "value": [...] } ] }
      • The order of uniforms in a block must match the order in the shader.
  • name as part of a uniform definition is no longer used.
  • value as part of a uniform definition replaces the old values, and the type depends on the type field.
    • This field is required.
    • "type": "int" needs "value": 123 (a single int).
    • "type": "float" needs "value": 123.4 (a single float).
    • "type": "vec2" needs "value": [1.2, 3.4] (two floats).
    • "type": "vec3" needs "value": [1.2, 3.4, 5.6] (three floats).
    • "type": "ivec3" needs "value": [1, 2, 3] (three ints).
    • "type": "vec4" needs "value": [1.2, 3.4, 5.6, 7.8] (four floats).
    • "type": "matrix4x4" needs "value": [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0] (four rows of four columns of floats).
• Post-process effect shaders
  • Instead of every uniform being an individual opaque type, they are now grouped in uniform blocks.
    • They will be set according to the pass definition in the JSON file, and may be shared across both vertex and fragment shaders.
  • The list of sizes (all vec2 *Size uniforms) are now replaced with a single SamplerInfo uniform block.
    • This contains, in order, the size of the output texture followed by the size every input texture.
    • The order of textures in the definition file will dictate the order of samplers in this uniform.
    • For most post chains this is just OutSize and InSize as before.
    • All sizes are vec2
• post/bits.fsh
  • Expects a BitsConfig of float Resolution and float MosaicSize.
• post/blit.fsh
  • Expects a BlitConfig of vec4 ColorModulate.
• post/blur.vsh and post/box_blur.fsh
  • Expects a BlurConfig of vec2 BlurDir and float Radius.
• post/color_convolve.fsh
  • Expects a ColorConfig of vec3 RedMatrix, vec3 GreenMatrix and vec3 BlueMatrix.
• post/invert.fsh
  • Expects a InvertConfig of float InverseAmount.
• post/rotscale.vsh
  • Expects a RotScaleConfig of vec2 InScale, vec2 InOffset and float InRotation.
• post/spiderclip.fsh
  • Expects a SpiderConfig of vec4 Scissor and vec4 Vignette.
• Globals uniform block
  • Available through #moj_import <minecraft:globals.glsl>
  • Most shaders are able to receive this uniform block, even if they don't normally use it.
  • Contains ScreenSize, GlintAlpha, GameTime and MenuBlurRadius.
    • MenuBlurRadius is the blur radius of the background when a menu is open.
• Fog uniform block
  • Available through #moj_import <minecraft:fog.glsl>
  • Most shaders are able to receive this uniform block, even if they don't normally use it.
  • Contains FogColor, FogShape, FogStart, FogEnd, FogSkyEnd and FogCloudsEnd.
    • FogSkyEnd is new and represents where the fog should end when drawing for the sky.
    • FogCloudsEnd is new and represents where the fog should end when drawing the clouds.
    • FogEnd is the "normal" fog cutoff as before.
  • FOG_IS_SKY is now available to the position.vsh/position.fsh shaders when they are rendering for the sky.
• Projection uniform block
  • Available through #moj_import <minecraft:projection.glsl>
  • Most shaders are able to receive this uniform block, even if they don't normally use it.
  • Contains ProjMat with no changes.
• DynamicTransforms uniform block
  • Available through #moj_import <minecraft:dynamictransforms.glsl>
  • Is no longer available to shaders that do not normally use it.
  • Contains ModelViewMat, ColorModulator, ModelOffset, TextureMat, LineWidth.
• Lighting uniform block
  • Available through #moj_import <minecraft:light.glsl>
  • Most shaders are able to receive this uniform block, even if they don't normally use it.
    • The values may not make sense if the shader wouldn't normally expect it, however.
  • Contains Light0_Direction and Light1_Direction.
• CloudInfo uniform block
  • Only available to the clouds shaders (rendertype_clouds.vsh/rendertype_clouds.fsh).
    • Contains CloudColor, CloudOffset and CellSize (new).
      • CellSize contains the size of an individual cloud cell.
• LightmapInfo uniform block
  • Only available to the lightmap shader (lightmap.fsh).
  • Contains AmbientLightFactor, SkyFactor, BlockFactor, UseBrightLightmap, NightVisionFactor, DarknessScale, DarkenWorldFactor, BrightnessFactor, SkyLightColor with no change in behavior.

• Reverted the fix for MC-101556: Nether Portal teleport range is too large (equivalent to a full block)

45 issues fixed

From released versions before 1.21

• MC-104231 – Loading a custom structure doesn't load rails correctly.
• MC-230902 – Black shapes sometimes appear in the end sky at low render distance
• MC-238931 – Clouds stop rendering before they are hidden by fog
• MC-256411 – Clouds not fully rendered depending on angle
• MC-257532 – Clouds don't fill the sky after 1.18 height change

From 1.21.1

• MC-277369 – The draft report icon isn't initially visible when saving a report as a draft.
• MC-277370 – The draft report icon doesn't initially disappear when a report is discarded.

From 1.21.5

• MC-279515 – The game stalls when running the /test clearall command with large radiuses.
• MC-280297 – The volume level between grass and dirt is inconsistent.
• MC-293754 – Minecraft causes OpenGL errors occasionally.
• MC-295395 – Entities interact differently with nether portals.
• MC-295677 – Title screen fades in from black after closing the "Welcome to Minecraft" screen.
• MC-295895 – 1.21.5 breaks minecart behavior when travelling through nether portals.
• MC-295944 – Reloading a professionless zombie villager causes it to gain random profession clothing.
• MC-296099 – Nether portal collision is or isn't working depending on the cardinal direction.
• MC-296121 – ClientboundLevelChunkPacketData buffer size is too big.
• MC-296348 – NoAI:1b mobs cannot be ridden in 1.21.5+.

From the previous development version

• MC-296353 – Potions, tipped arrows, and dyed leather armor render with missing or incorrect colors in the inventory.
• MC-296355 – Characters in front of the cursor render one pixel too far to the left.
• MC-296356 – Hitbox rendering in GUIs is broken.
• MC-296357 – Happy ghasts produce footstep sounds when flying close above blocks.
• MC-296358 – A player in Spectator mode on top of a happy ghast makes it stop moving.
• MC-296363 – Scrolling in the experiments screen does not move the positions where the buttons can be selected.
• MC-296365 – Block placing sounds are played when the block states of completely unhydrated dried ghasts are changed.
• MC-296366 – Kicked for flying while flying happy ghast.
• MC-296367 – The enchantment glint in the inventory appears on all items of the same type.
• MC-296373 – The side faces of dried ghast tentacles aren’t culled when covered by blocks.
• MC-296376 – Sounds produced by ghastlings can be heard from too far away.
• MC-296381 – Dried Ghasts always face north in world generation.
• MC-296382 – Filled maps are blurry.
• MC-296401 – Harnesses are not sorted correctly in the Creative Inventory.
• MC-296419 – Spectators' names in multiplayer tab list render improperly compared to 1.21.5.
• MC-296426 – Text background lacks opacity over hotbar icons.
• MC-296427 – Happy ghasts move/spin erratically when leashed to a fence.
• MC-296434 – Unable to see items when hovering over them inside of a bundle.
• MC-296437 – Items render behind effect icons and recipe book inside of the inventory.
• MC-296444 – Blur is applied to resource pack icons.
• MC-296465 – Highlighting text on a sign causes it to override the sign background.
• MC-296467 – Item tooltips cause items behind it to not render.
• MC-296470 – Items render behind text in anvils.
• MC-296471 – Hud is now hidden while in bed resulting in delayed hud rendering.
• MC-296517 – The menu panorama turns gray when the switching realm worlds interface is open.
• MC-296518 – Text inside the middle of the java realms information box completely disappears when selected.
• MC-296524 – Server and singleplayer world icons are blurry.
• MC-296638 – Clocks, compasses, and lodestone compasses do not render enchantment glint in certain display contexts when using Fabulous! graphics.