Commands & Data guides
Guides to Minecraft commands and the data behind them: /give components, scoreboards, loot tables, damage types, /fill limits and anvil costs.
How to enable data packs in Minecraft: new worlds, old worlds, servers
Where a data pack goes, how it gets switched on in each case, the /datapack commands and the quoting they need, and the Experiments packs you can never add later.
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.
Post effects and loot pools: the two halves of one chest
A loot pool's weights decide what drops; the /posteffect command decides how it feels. Both are numbers you can check before writing the datapack.
The same red text breaks on Java and Bedrock
A colour code that renders perfectly in one plugin shows up as literal ampersands in the next. The format is the reason, not the plugin.
A custom head stores a URL wrapped in base64 JSON, not an image
The profile component holds base64 of {textures:{SKIN:{url:…}}}. That is why a head's look is fixed at the moment it was made, and why the database can be tens of thousands of entries.
A Minecraft username is 1–16 characters of exactly three things, and a UUID has two spellings
Letters, digits, underscore. No hyphens, no dots, no spaces. And a UUID is accepted with or without its dashes — which is why one lookup fails and the identical one works.
A predicate with one condition has no wrapper, and that is a real shape change
One condition is the object itself. Two or more get wrapped in all_of or any_of. Plus the eight condition types, and why inverting is a wrapper rather than a flag.
A .nbt structure stores palette indexes, not block names — which is why it is so small
Three keys hold an entire build: size, palette and blocks. Each block is an integer pointing into the palette, so a 32³ volume of stone costs one string and 32,768 small entries — a position and an index each, never a name.
The advancement tree: 126 advancements, and Story has no challenges at all
Adventure holds 47 of the 126 and the End just 9. 70 are dead ends, the longest chain is 8 deep, and the Story tab is the only one with zero challenge frames.
Damage types: which 19 ignore armour, and why shields are the weaker guard
26.3 ships 51 damage types. 19 bypass armour, 30 bypass shields, and the overlap is not what people assume — every type that beats armour also beats a shield.