The official name for the update, the Combat Update, was discovered on April 1, 2015 by Reddit user 3dDeters (and several others independently) who found a QR code hidden in the snow falling pattern of the April Fools 15w14a snapshot.
Development on the Combat Update began at least a month before the Bountiful Update was released. The development period was over twice as long as the development period for 1.8 at 576 days; 2015 became the first year where a major update to Minecraft: Java Edition was not released. Snapshots began the day after 1.8.8 was released. 56 development snapshots were released, from 15w31a to 16w07b, making it the update with the most snapshots so far. The time between releases of 1.8 and 1.9 represent the longest time span between major updates, at 545 days. Fifteen iterations of the launcher were released during this period, from 1.5.2 to 1.6.59. 1.8.9 was also released during this period.
The development team called the release feature-complete by the end of October 2015, and started a lengthy period of gameplay balancing and bug-fixing. They later announced that 1.9 would not be released in 2015, as the developers "want to fix more bugs before release, and keep the game stable over the holidays".
Mojang released the first pre-release on February 17, 2016. The date for this was hinted at by the image in the blog post that announced snapshot 16w06a. The data values of the wool in the image were (1, 7, 0, 2, 2, 0, 1, 6), having a possible (though never confirmed) interpretation of "17-02-2016", a date just one week from 16w06a. The second pre-release was released on February 18th, the third pre-release was released on February 24, and the fourth pre-release was released on February 26.
- A method of restarting the ender dragon boss fight.
- The infinite generating outer islands of the End, populated by chorus trees, end city structures and ships, and shulker mob.
- "Off-hand" slot for dual wielding.
- Attack strength mechanic.
- Attribute system expanded.
- Shield, spectral arrow, 14 types of tipped arrow and a lingering potion for each type of potion.
- Elytra for Gliding .
- Dominant hand option.
- Igloo structures that generate in cold biomes.
- Skeleton trap horses that spawn during thunderstorms.
- 13 new blocks: grass path, frosted ice, 2 new types of command block, chorus flower and chorus plant, end gateway block, end rod, end stone brick, purpur block, pillar, slab and stairs.
- New items: beetroot with seeds and soup, end crystal, normal and popped chorus fruit, luck potion and dragon's breath.
- 5 new splashes.
- 4 new particles:
- 4 new status effects:
- 2 new enchantments:
- Frost Walker and Mending
- 5 new statistics:
- Lots of new NBT tags.
- 3 new gamerules.
- 150+ new sound events.
- Support for Chinese, Japanese and Korean, and probably other IME languages.
- Changed the layout of the end island pillars and the ender dragon boss fight.
- Skeleton AI is more difficult.
- Sword blocking removed, and several other weapon techniques added.
- Tool damage is rebalanced.
- Sharpness and protection enchantments are nerfed.
- Status effect icons are now visible on the main screen.
- Health regeneration is rebalanced.
- Fishing is rebalanced.
- Brewing stands now require blaze powder.
- Enchanted golden apples are no longer craftable.
- Maps changed.
- Healing system based on saturation.
- Attack cool down on melee tools and weapons.
- Loot found in chests generated in the world is rebalanced.
- Death in hardcore mode allows the player to continue in spectator mode.
- Boats are improved.
- Stronghold generation increased to a maximum of 128 strongholds.
- Large oak trees generate in forests again.
- Increased fire spread while raining.
- Glass panes and iron bars have a thin appearance when not connected, as opposed to a crosslike appearance.
- Mobs and players now push one another around.
- Death message is now displayed on the death screen.
- Mob and player heights are slightly modified.
- Resource packs can specify models depending on damage value, item state, and hand.
- Structure data now comes from /assets/structures.
- Loot from mobs, fishing and chests is now determined by loot tables.
Performance and optimizations
- Particles are no longer entities
- Block ticking
- Mob pathfinding
- Memory usage when connected to servers
- As the trend has been since version 1.2, the update notes say "Removed Herobrine", despite the fact that Herobrine was never part of the game.
- This update is often considered the most controversial one to Minecraft (at least on Java Edition) due to the new unpopular combat mechanics.
- The name for the update was teased in the joke snapshot 15w14a with a QR code.
- This is the only update to date that released on leap day (February 29th) and is guaranteed to remain that way until at least 2024 (assuming no alterations are made to the calendar).
- 1.9.1 added elytra sound effects, the
generic.armorToughnessstat, and maThisde the crosshair attack indicator visible by default, as well as other minor changes and bugfixes.
- 1.9.2 was released soon thereafter to fix a crash in 1.9.1, when riding boats and minecarts on Realms servers.
- 1.9.3 was released to fix several stability issues, add the
/stopsoundcommand, and to implement a blacklist for servers not in conformance with the Minecraft EULA.
- 1.9.4 was released soon thereafter to fix an erroneous Realms warning.
- "We've updated the release date for Minecraft 1.9 to February 29! Why? Because it's Leap Day!" – @jeb_, February 23, 2016
- "Darn, I hoped this would go unnoticed for a few days. Well spotted, @3ddeters. http://www.reddit.com/r/Minecraft/co …" – @Dinnerbone, April 1, 2015
- "@MushirMickeyJoe @erismetis We started working on 1.9 before we released 1.8. Therefore, "1.9 started" minus "1.8 released" is negative! :D" – @Dinnerbone, October 15, 2015
- "@MushirMickeyJoe @JordanFisher_YT Negative month or two. We started working on 1.9 long before we released the first snapshot." – @Dinnerbone, October 15, 2015
- "We are aiming to get Minecraft 1.9 feature complete at end of this month. Feature complete doesn't mean bug free & ready to release, though!" – @Dinnerbone, October 15, 2015
- "Update: Minecraft 1.9 will not be released this year. We want to fix more bugs before release, and keep the game stable over the holidays" – @jeb_, November 24, 2015