This weeks snapshot brings us bug fixes! Lots of bug fixes.

Changes in 17w49a

Added new data concept: 'tags'

Lots of bug fixes!

Tab now also cycles the command suggestions again

Fixed bug MC-99321 - Hoppers cannot pull items from double chests if second chest is blocked

Fixed bug MC-121282 - Server icons erased on loading multiplayer menu

Fixed bug MC-121631 - Taking items from the creative inventory search tab no longer resets search text

Fixed bug MC-121632 - Pressing "chat" key selects search in creative inventory/recipe book AND types the letter

Fixed bug MC-121648 - "Difficulty" in settings is untranslated and lowercase

Fixed bug MC-121665 - Key "None" display string as "key.keyboard.-1"

Fixed bug MC-121705 - Cursor is offset from actual mouse location when opening GUIs while moving mouse

Fixed bug MC-121709 - The clickable area to sort the statistics menu are not in the right place

Fixed bug MC-121714 - Unable to save screenshot of PNG format

Fixed bug MC-121718 - You can not select the spectator menu

Fixed bug MC-121808 - Command argument validation for single entity says player in some error messages

Fixed bug MC-121873 - Dark background missing from beacon GUI

Fixed bug MC-122148 - No Block, Item, Mob, GUI, or any other texture renders -- No sounds play

Fixed bug MC-122270 - Pushing blocks with connections doesn't update them

Fixed bug MC-122295 - Backups folder is created outside of the server directory when using a dedicated server

Fixed bug MC-122309 - '/gamerule gameLoopFunction' does not tab complete function names

Fixed bug MC-122314 - All maps created in earlier versions are now the same

Fixed bug MC-122355 - Crash on breaking banner: java.lang.ClassCastException: arw cannot be cast to aru

Fixed bug MC-122383 - Pre-existing chests invisible, overlapping

Fixed bug MC-122395 - Custom player heads are called "block.minecraft.player_headnamed"

Fixed bug MC-122492 - Debug stick can be used by non-op players

Fixed bug MC-122521 - Damaged anvil always turns to the North

Fixed bug MC-122536 - "set_nbt" function in loot table does not merge NBT to item

Fixed bug MC-122558 - Health criteria scoreboard objectives do not use hearts to display value anymore

Fixed bug MC-122573 - Crash due to carpet and sticky pistons

Fixed bug MC-122584 - Incorrect format string order in statistics

Fixed bug MC-122625 - Order of contents of north- and east-facing double chests changed after update

Fixed bug MC-122639 - Can't place lily pads on ice

Fixed bug MC-122643 - Snow, carpet and daylight detectors culling adjacent upper slabs

Fixed bug MC-122644 - Datapacks cannot replace vanilla crafting recipes.

Fixed bug MC-122646 - Attempting to add cullface to glass panes does not work

Fixed bug MC-122650 - Player heads aren't affected by upgrade paths, renamed to "block.minecraft.player_headnamed" + head texture does not show, only when placed

Fixed bug MC-122718 - Dirt border of "video settings" menu encroaching too far on settings

Changes in 17w49b

Added tags for functions

Removed the "game loop" gamerule, now anything tagged in minecraft:tick will run every tick

will run every tick Ticking functions now run before the world, not after

When overriding a tag, you now append instead of replacing

Fixed bug MC-100579 - Pistons do not account for block updates triggered by blocks broken by the extending piston when placing moved blocks, resulting in duplication issues

Fixed bug MC-122196 - Language options are blank

Fixed bug MC-122711 - Piston leave their head behind

Fixed bug MC-122725 - Unable to duplicate banners in crafting table

Fixed bug MC-122889 - The name of the chiseled sandstone recipe is cut_sandstone, not chiseled_sandstone

Fixed bug MC-122910 - New block/item tags don't work in commands

Fixed bug MC-122914 - The texture of the lava and water is invisible when there is a block above

Fixed bug MC-122916 - team color commands don't work properly

Fixed bug MC-122918 - Log crafting recipes produce one plank

Fixed bug MC-122924 - Wrong crafting recipe output for granite and andesite

Fixed bug MC-122925 - Opening spectator menu crashes the client

Fixed bug MC-122931 - Frost walker freezes all water, even if there are mobs in the water

Fixed bug MC-122935 - hang on 'waiting for chunk' and/or fatal background exceptions when teleporting to new chunks in a busy gameloop

Tags

Items & blocks can be "tagged" with an ID, to make testing for things much easier. For example, checking if a block is "wool" with a command needs to actually test for every wool-like block individually. Now you can test if it matches the tag minecraft:wool, instead.

Types of tags

Currently there's block tags and item tags. You use block tags when testing for blocks in the world, and item tags for testing for items (even block-items) in inventories. It may seem like we could just stick with item tags, but not every block has an item!

Creating tags

Inside data packs, you can create a file at data/(namespace)/tags/blocks/foo.json to make a block tag called namespace:foo, which contains a list of blocks that should be tagged with namespace:foo.

A work in progress

There's not many default tags (both item & block have minecraft:planks and minecraft:wool currently, that's it). We're migrating things over to it, still.

Recipes

Recipes can now refer to a tag instead of an item. This should save a few hundred thousand lines of code, somewhere.

Install the snapshot

Please report any and all bugs you find in Minecraft to bugs.mojang.com. If nobody reports a bug, we can't fix it!

To get snapshots, open your launcher and go to the "launch options" tab. Check the box saying "Enable snapshots" and save. To switch between the snapshot and normal version, you can find a new dropdow menu next to the "Play" button. Back up your world first or run the game on in a different folder (In the "launch options" page).

Snapshots can corrupt your world, please backup and/or run them in a different folder from your main worlds.

Cross-platform server jar:

Report bugs here: