Minecraft 26.4 Snapshot 1: Vulkan default, sulfur caves in old worlds
What the first 26.4 snapshot changes, from Mojang's changelog and our diff of its jar against 26.3: 1,525 data files touched, 1,499 of them only a version stamp.
The first Java snapshot for 26.4 went out on 22 September 2026, a week after 26.3. Mojang's changelog calls it "a range of technical updates and improvements". Below are the headline changes as the changelog states them, then what a file-by-file comparison of the snapshot's client jar against 26.3's actually finds.
Vulkan becomes the default
The Graphics API video setting keeps its three choices, but Default now behaves the same as Prefer Vulkan, where in 26.3 it meant OpenGL. The changelog adds that the game no longer changes the setting by itself after a crash on start-up. In the jar the change is visible in the text: 26.3 labels the option "Prefer Vulkan (Experimental)", and the snapshot adds a plain "Prefer Vulkan" label beside it.
If the game misbehaves after updating, Prefer OpenGL is still one click away in Video Settings, and changing it needs a restart.
Sulfur caves reach old worlds
Worlds created before Caves & Cliffs get new terrain generated below their old chunks when they are upgraded, and that retrogeneration now includes sulfur caves. The snapshot adds exactly two data files, both biome tags that drive it:
| new tag | contents |
|---|---|
#minecraft:is_cave | lush caves, deep dark, dripstone caves, sulfur caves |
#minecraft:generated_in_below_zero_retrogen | #minecraft:is_cave |
Sulfur caves are not new themselves: comparing release jars, worldgen/biome/sulfur_caves.json first appears in 26.2.
Smaller gameplay changes
- Mushrooms — red and brown — can be placed on any block with a solid top, in any light. They still only spread when the brightness is below 13, unless the block under them allows it.
- Water no longer makes you jump by itself: several long-standing bugs where players and mobs auto-jumped against blocks in water, or when falling into it, are fixed.
/fillbiomenow fills biomes with block accuracy.
For servers
Three new server.properties fields, per the changelog:
| field | what it does |
|---|---|
allowed-connection-ids | if set, only clients whose server address carries a matching id get in — or even see the server's status |
status-contact-details | text sent with the server status as a way to reach the owners |
enable-legacy-status | set it to false to drop the pre-1.7 status and ping protocol; the default, true, keeps things as they were |
The id comes from the address players type. A server address can now carry properties after a ?, like a URL query, and myid@play.example.com is shorthand for play.example.com?_id=myid. The snapshot's text gains a matching new message, too: "Connection rejected by server".
For pack makers
| 26.3 | 26.4 Snapshot 1 | |
|---|---|---|
| data pack format | 121.0 | 122.0 |
| resource pack format | 97.1 | 98.0 |
| world version | 5023 | 5119 |
| Java | 25 | 25 |
Worldgen data changed shape in places: noise settings lose their default_block field (it is always air now, and stone or netherrack come from the material rules), and the cuboid placement now means what its size says — an xz_size of 2 is 2 × 2, not 3 × 3. The one vanilla file that uses it, the warm-ocean coral feature, had its sizes raised from 3–5 to 4–6 to keep coral patches the same size. Custom worldgen packs that use cuboid need the same +1.
What the jar diff actually finds
Comparing every file in the two client jars:
| 26.3 | snapshot | added | removed | changed | |
|---|---|---|---|---|---|
| data files | 9,884 | 9,886 | 2 | 0 | 1,525 |
| asset files | 11,604 | 11,604 | 0 | 0 | 11 |
1,525 changed data files sounds like a rewrite, and it is not. 1,511 of them are structure templates, and after unzipping them 1,499 differ only in the data version number stored inside the file — 5023 became 5119, which the game writes into every saved structure. Twelve templates have real edits: the End city ship, the igloo's bottom room, two pillager outpost watchtowers, four trial chamber pots, one trial chamber intersection and one taiga village house. The remaining changed data files are the three experiment packs' version bump, seven noise settings, three material rules and the coral feature.
On the asset side, eight of the eleven files are shaders, two are language files, and one is desert_pyramid_map.png — the one-pixel fix from bug MC-311582. The English text gained three strings and reworded four, mostly writing out "Control" and "Command" instead of "Ctrl" and "Cmd".
Snapshots can corrupt worlds; Mojang's advice is to back up and to run them in a separate folder. To compare releases rather than snapshots, the version comparison in our Version Changelog & Splash Text Archive lines up what changed between Minecraft versions.