In this week's snapshot, we are bringing a long-awaited feature into parity as fallen trees are making their debut in Java Edition. Additionally, firefly bushes can now generate in mangrove swamps and rarely in badlands.

On the technical side, SNBT syntax in commands has been expanded and improved, including fixing bugs related to SNBT text components preventing escapes from working.

New Features

• Added fallen trees to be in parity with Bedrock Edition

Fallen Trees

• Fallen trees are a new decorative variant of trees
• Fallen trees come in four different wood type variants:
  • Oak
  • Birch
  • Jungle
  • Spruce
• Birch fallen trees can come in a shorter version or a longer version
• Some fallen trees can be decorated with mushroom or vines
• Fallen trees can be found in all biomes where their standing tree variant grow, except the following:
  • Meadow
  • Bamboo Jungle
  • River
  • Grove
  • Flower Forest has fallen birch trees but not fallen oak trees

Changes

Leaf Litter

• Leaf Litter is now replaceable by other blocks

Firefly Bush

• The Firefly Bush can now generate near water in Mangrove Swamps and Badlands (very rarely), like other biomes with water

Technical Changes

• The Data Pack version is now 69
• New command line argument --renderDebugLabels is available for the client
  • Adds debug labels to relevant OpenGL objects, making debugging rendering easier for developers

Data Pack Version 69

• Object notation used in commands for NBT, text components and inline predicates (a.k.a. SNBT) has been extended

Commands

• /data can now create and modify heterogeneous lists transparently

Entity Data

• The FallFlying field will no longer be preserved if removed
• The Health and Air fields now default to their respective maximum value if not specified

area_effect_cloud

• The Duration field now defaults to -1 if not specified
• If the Duration field is -1, the Area Effect Cloud will never run out
• This means that an Area Effect Cloud summoned with no duration specified will no longer immediately disappear

creeper

• The Fuse field now defaults to 30 if not specified
• The ExplosionRadius field now defaults to 3 if not specified

dolphin

• The Moistness field now defaults to 2400 if not specified

ender_dragon

• The DragonDeathTime field now defaults to 0 if not specified

falling_block

• The BlockState field can now be air (will despawn immediately) - if otherwise not specified or invalid, defaults to sand
• The HurtEntities field now defaults to false if not specified (or true if BlockState is anvil)
• The FallHurtAmount field now defaults to 0 if not specified
• The FallHurtMax field now defaults to 40 if not specified
• The DropItem field now defaults to true if not specified
• The TileEntityData field will no longer be preserved if removed

firework_rocket

• The ShotAtAngle field now defaults to false if not specified

fox

• The Trusted field now defaults to empty if not specified (and will no longer be merged with the previous state if modified by /data)

ghast

• The ExplosionPower field now defaults to 1 if not specified

goat

• The HasLeftHorn and HasRightHorn fields now default to true if not specified

interaction

• The width and height fields now default to 1 if not specified

item

• The Health field now defaults to 5 if not specified
• The PickupDelay field now defaults to 0 if not specified
• The Age field now defaults to 0 if not specified
• The Owner and Thrower fields will no longer be preserved when removed

item_frame and glow_item_frame

• The ItemDropChance field now defaults to 1.0 if not specified

primed_tnt

• The fuse field now defaults to 80 if not specified
• The explosion_power field now defaults to 4 if not specified

shulker

• The Color field now defaults to 16 (no color) if not specified

skeleton

• The StrayConversionTime field will no longer be preserved when removed

spectral_arrow

• The Duration field now defaults to 200 if not specified

snow_golem

• The Pumpkin field now defaults to true if not specified

tnt_minecart

• The fuse field now defaults to 80 if not specified
• The explosion_power field now defaults to 4 if not specified
• The explosion_speed_factor field now defaults to 1 if not specified

trader_llama

• The DespawnDelay field now defaults to 47999

villager

• The FoodLevel and Xp fields now default to 0 if not specified
• The ConversionTime field will no longer be preserved when removed

wandering_trader

• The DespawnDelay field now defaults to 0 if not specified

zombie

• The DrownedConversionTime field will no longer be preserved when removed

zombie_villager

• The Xp field now defaults to 0 if not specified
• The ConversionTime field will no longer be preserved when removed

arrow, spectral_arrow, trident

• The damage field now defaults to 2 if not specified

dragon_fireball, wind_charge, breeze_wind_charge, wither_skull, small_fireball, and large_fireball

• The acceleration_power field now defaults to 0.1 if not specified

small_fireball and large_fireball

• The ExplosionPower field now defaults to 1 if not specified

block_display, item_display, and text_display

• The interpolation_duration, teleport_duration, and start_interpolation fields now default to 0 if not specified
• The view_range field now defaults to 1 if not specified
• The shadow_radius field now defaults to 0 if not specified
• The shadow_strength field now defaults to 1 if not specified
• The width and height fields now default to 0 if not specified

Block Entity Data

campfire

• The CookingTimes and CookingTotalTimes fields will no longer be preserved when removed

chiseled_bookshelf

• The last_interacted_slot field now defaults to -1 if not specified

hopper

• The TransferCooldown field now default to -1 if not specified

jigsaw

• The name, target, and pool fields now default to minecraft:empty if not specified
• The final_state field now defaults to minecraft:air if not specified

sculk_shrieker

• The warning_level field now defaults to 0 if not specified

structure_block

• The ignoreEntities and showboundingbox fields now default to true if not specified
• The posY field now defaults to 1 if not specified

NBT changes

• Any interface with NBT data within the game (SNBT representation, /data) now supports heterogeneous lists, i.e. ones where elements are not of the same type
  • Inserting or replacing into a list of a different type with /data will no longer give an error
  • Inserting into an array type (e.g. [I;1,2,3]) is still type-restricted
  • This means that the 'wrapper' objects previously used to represent heterogeneous lists will no longer be observable by in-game means
• /data can no longer traverse paths with an empty key (e.g. /data get ... foo.''.bar)
• The NBT file format is unchanged:
  • Heterogeneous lists are transformed before storage to bypass NBT constraints
  • Example transform: ['a', {'b':3}] is stored as [{'':'a'},{'b':3}]
  • Existing external tools will still be able to read NBT files as before, but heterogeneous lists will be displayed in the transformed form
• No data produced by the game has changed: objects such as Text Components were already producing heterogeneous lists in this form
• Note: these wrapper objects may never be observed in-game, they are only relevant to developers working with the NBT file or network format directly

SNBT Changes

• The text format for describing object-like data in commands (like NBT, text components, predicates, etc.) has been extended

Number Format

• Either whole or fraction parts of a float number can be omitted
  • Examples: .1 and 1. are valid now
• Float numbers now use E notation
  • Example: both 1.2e3 and 1.2E3, 1.2E+3, 12000e-1 are now a valid way to represent 1200.0
• Integer numbers can now be prefixed with 0x to represent hexadecimal numbers and 0b to represent binary numbers
  • Example: 0xbad (equal to 2989), 0xCAFE (equal to 51966), 0b101 (equal to 5)
• Integer numbers now can't start with 0
  • Normally it would mean number is in base-8, but we are restricting it to avoid accidental use
• Numbers can now contain _ character between sequences of digits (but not at the start or the end of sequence)
  • Example: 0b10_01, 0xAB_CD, 1_2.3_4__5f, 1_2e3_4
• NaN, Inf or hexadecimal float representation are NOT supported
• Type suffixes have been extended:
  • Integer type suffixes (b or B - byte, s or S - short, i or I - integer, l or L) can now be prefixed with s (signed) or u unsigned
  • New suffixes only affect valid range when parsing - values are still stored as signed
    • Example: 240ub is equal to -16sb, while 240sb does not parse
  • When a suffix is used without u or s, it defaults to signed for decimal numbers and unsigned for binary and hexadecimal numbers
  • Note: since b is also a valid hexadecimal digit, byte sized hexadecimal values can only be written with a signed suffix, like 0x11ub or 0x11sb

Strings

• Quoted strings can now use escape sequences beyond \', \" and \\:
  • Unicode escapes:
    • \x - two digit escape, like \x42
    • \u - four digit escape, like \u2603
    • \U - eight digit escape, like \U00002603
    • \N{<name>} - named Unicode character, like \N{Snowman}
  • Built-in escape sequences:
    • \b - backspace, Unicode \x08
    • \s - space, Unicode \x20
    • \t - horizontal tab, Unicode \x09
    • \n - linefeed, Unicode \u0a
    • \f - form feed, Unicode \u0c
    • \r - carriage return, Unicode \u0d
• Unquoted strings now can't start with 0-9, ., +, - to avoid accidental collision with numbers

Number arrays

• Values in arrays ([B;], [I;], [L;]) without a suffix are now assumed to have suffix matching the type of the array
  • Example: [B;1,2] is equivalent to [B; 1b, 2b]
• Arrays can now also accept types smaller than the array type
  • Example: [I;1b,2s,3] is valid and equivalent to [I;1i,2i,3i]

Lists

• Lists now accept trailing commas
  • Example: [1,2,] is valid and equivalent to [1,2]
  • Only one trailing comma is allowed, and it must come after a valid element - both [,] and [1,,] are invalid

Compounds

• Compounds (maps) now accept trailing commas
  • Example: {a:b,}
  • Only one trailing comma is allowed, and it must come after a valid key-value pair - both {,} and {a:b,,} are invalid

Fixed bugs in 25w09a

• MC-168262 Dead bushes cannot be placed on farmland
• MC-236100 End crystal beam appears to be black
• MC-276861 The player can sometimes teleport through blocked end portals when moving very fast
• MC-279229 SNBT text components prevent \n and \t from working
• MC-279236 Flying into water with an elytra puts the player into an erroneous state
• MC-279250 SNBT text components prevent unicode escapes from working
• MC-279252 Changing a single line of a sign with /data is no longer possible in some situations
• MC-279278 Strafing twice in rapid succession while walking forward causes player to sprint
• MC-279928 Beacon beam clips into beacon block when far enough away
• MC-279932 Beacon beam disappears and reappears when approaching it
• MC-279942 Beacon beam can render over fog when outside render distance
• MC-279947 Snout of the new cow model is offset vertically by 0.1 pixels
• MC-280022 Players can be lit by lava while stepping onto solid blocks next to it
• MC-280033 Beacon beams render beyond client render distance
• MC-280121 Leaf litter can be placed on walls and fences
• MC-280123 Short dry grass and tall dry grass aren't randomly offset, unlike similar blocks
• MC-280155 Random ticks can cause entity build-up in lazy chunks
• MC-280170 Goats can no longer ram armor stands unless the game rule mobGriefing is set to false
• MC-280211 End crystal beams cause OpenGL errors with glDebugVerbosity set to 3