Minecraft Snapshot 25w45a Adds Timelines for Hosts

Mojang released Java Edition test build 25w45a on 4 November 2025, bringing the final feature set for the Mounts of Mayhem drop alongside foundational technical additions. The update moves the data pack version to 93.0 and the resource pack format to 73.0. For admins tracking the release cycle across the Minecraft server list, the arrival of minecraft snapshot 25w45a introduces experimental timeline files, splits core item textures out of existing atlases, and expands mount options with Netherite horse protection.

Combat and Mount Additions

Mounts of Mayhem receives its highest gear rank and several combat adjustments in this build.

Netherite Horse Armor and Mobility

Players can upgrade Diamond Horse Armor using a Smithing Table to craft Netherite Horse Armor, offering increased survivability for mounted encounters. In parallel, spear balance has been retuned: charging attacks now penalise players more severely whenever a thrust fails to connect. The release also adds the Mob Kabob advancement, earned by impaling five targets during a single charge attack.

Ocean and Desert Mob Variants

Warm ocean biomes now feature the Coral Zombie Nautilus, which naturally replaces standard variants in those waters. Camel Husks drop two to three pieces of Rotten Flesh upon death, scaling up by zero to one for every level of Looting. Additionally, interaction persistence has widened: Zombie Horses, Camel Husks, and Nautili no longer require a player to ride them to prevent despawning, as any direct player interaction now marks them persistent.

Data Pack Timelines and Variant Mechanics

Snapshot 25w45a introduces experimental systems that let custom packs alter game systems dynamically based on world time.

Timeline Registries

Defined under data/<namespace>/timeline/<id>.json, timelines adjust mechanics according to the absolute day time set by /time set. Timelines supply Environment Attribute modifiers using priority processing: Dimension settings apply first, followed by Biomes, Timelines, and finally non-data-driven Weather. Configured timelines can repeat over an optional period_ticks integer, shifting attributes between keyframes using built-in easing modes—including linear, step, and cubic Bézier curves—or remaining fixed on discrete ticks.

Data-Driven Nautili

Server creators can define custom Zombie Nautilus mobs under data/<namespace>/zombie_nautilus_variant/<id>.json. Each variant configures model structures, texture paths pointing to custom assets, and rules matching biomes, moon illumination, or structures. Similar custom mob work expanded in earlier snapshots like Minecraft 26.1 snapshot 4, but 25w45a specifically opens Nautilus variants to data packs.

Breaking Technical Changes for Server Hosts

Upgrading a testing instance to snapshot 25w45a requires manual intervention for custom content, command setups, and data-pack rules.

Texture Atlas Command Breaks

Item textures have been separated from the blocks atlas into their own dedicated items atlas. Any command blocks, custom plugins, or rendering pipelines referencing the block sheet to pull item textures must be redirected to the items atlas to avoid display failures. Hosts maintaining custom packs should also review related work from Minecraft 1.21.11 pre release 1 as reach parameters evolve.

Rule Limits and Component Bounds

Component validations have been tightened: both minecraft:piercing_weapon and minecraft:kinetic_weapon now restrict min_reach and max_reach between 0.0 and 128.0, while hitbox_margin accepts floats from 0.0 to 1.0. For server configurations, the minecraft:max_entity_cramming gamerule now enforces a hard floor minimum of 0. Existing configurations specifying negative integers will fail validation.

Player-Facing Visual and Audio Tweaks

Players logging into a 25w45a world will notice revised environmental transitions. Sunrise and sunset atmospheric shades now shift dynamically when obscured by rain or active thunderstorms. Memory pressure from anisotropic filtering has been reduced for client graphics allocations, though overall video memory footprint remains high. The start screen panorama has also shifted to display the completed Mounts of Mayhem drop backdrop.