Minecraft Experimental Datapack

Experimental Content

This content applies only to Java Edition.

Experiments are built-in datapacks unique to Java Edition. Enabling them lets players try unfinished or in-development features that may ship in future versions.

Enabling

Experimental options can be enabled at world creation under "Experimental" or "Datapacks"; they cannot be disabled afterwards, and existing worlds cannot enable them. Enabling a built-in datapack activates the hardcoded game elements controlled by feature flags plus the datapack content under data/<namespace>/datapacks/<experiment ID>/. On servers, set initial-enabled-packs and initial-disabled-packs in server.properties.

Warning

Experimental features may be incompatible with future versions, potentially crashing, corrupting, or preventing loading of the world; a warning is shown in both menus.

Options (as of 26.2)

• Minecart improvements: game rule max_minecart_speed (default 8, max 1000 blocks/s); "synchronize minecart rotation" accessibility option (default off); minecarts have inertia (keep vertical momentum and tilt off slopes), and align to rails.
• Redstone experiments: changes to redstone dust update order.
• Villager trade rebalancing: rebalanced armorer and librarian trades.

Feature flags

Feature flags enable/disable groups of feature elements per world. They filter items, blocks, entities, screen types, potions, and mob effects across registries:

• Filtered blocks: unrecognized by /setblock//fill; cannot be used or picked; their properties don't load with entities; block entities don't generate in structures/features.
• Filtered entities: unrecognized by /summon; don't spawn/load; spawn eggs (including dispenser use) and spawners don't work.
• Filtered items: unrecognized by /give//item//clear; hidden in creative; tooltip shows red "Disabled Item"; unusable; recipes/loot don't produce them (item entities can still exist).
• Filtered game rules: unrecognized by /gamerule. Effects: not assignable via /effect. Enchantments: not via /enchant. GUIs not loaded; stats not shown; commands not parsed. Mechanism-modifying elements only apply when the flag is on.

A feature flag set holds at most 64 flags. Current flags: vanilla (default on), trade_rebalance, redstone_experiments, minecart_improvements. Saves with experiments record enabled_features in level.dat; without experiments the tag is absent.