Java Edition 1.9.1

1.9.1^[1] is an upcoming update for Minecraft with no set release date. 1.9.1 will not be compatible with 1.9 servers.

Additions

Added elytra sound effects.
- Sound event item.elytra.flying
Armor attribute generic.armorToughness
- Damage formula is now damage = damage * ( 1 - max( defensePoints / 5, defensePoints - damage / ( 2 + toughness / 4 ) ) / 25 ), i.e. increased toughness means less armor defense point reduction from strong attacks.
- Diamond armor has toughness 2, all other armor has toughness 0. A full set of diamond armor therefore gives a toughness attribute of 8.
New option enableWeakAttacks in options.txt
- Defaults to false. When false, the client will ignore attempts to attack when weapon cooldown is less than 75% recharged.

Session ID is now no longer printed by the game to the log files or to the launcher.^[2]
Entity selector c (count) now sorts on proximity using true coordinates, not coordinates snapped to the grid.^[3]
Loot tables now also work in dispensers and droppers
- Dispensers with arrows in jungle temples now use loot tables.
Hoppers can now push and pull items to and from blocked chests.
Increased limit per tick for scheduled tile ticks from 1,000 to 65,536.
Improved AI.^[verify]
Shields no longer take damage when blocking weak attacks (less than 3 damage).
The title of the inventory of Minecarts with Chests and Minecarts with Hoppers now match the item's name.

MC-7961 – Hopper can't fill or empty a chest if the chest is blocked from opening.
MC-56162 – Setting /worldborder damage amount 0 doesn't work.
MC-95352 – Spatial target arguments c, dx, dy, dz behave unexpectedly and inconsistently.

MC-90257 – A chain of command blocks may take more than 1 tick to traverse.
MC-96219 – Block duplication bug with pistons (ghost blocks).
MC-96927 – Selector c Targeting Inaccurate Entity Position
MC-98327 – Elytra texture transparency issues.
MC-98461 – Several languages (at least Frisian, Talossan, Ripuarian, Lojban, and LOLCAT) are not selectable, "Eesti (Eesti)" is listed as "Inglise (US)"
MC-98587 – Command block logic sometimes fails arbitrarily
MC-99060 – Elytra glowing effect is always black.
MC-99697 – Typos in minecarts with hoppers and chests, reading "container.minecart"

Fixed game engine adding non-existent entities (failed mob spawns, etc.) to its internal lists, increasing instability.^[4]