Java Edition removed items

Blocks previously obtainable as items
The game prevents certain blocks from being obtained through normal gameplay methods, such as crafting, the creative inventory, the pick block key, and the Silk Touch enchantment. It also prevents such blocks from being given through less conventional methods, such as inventory editing, mods, and commands. Until 1.7.2 and 1.8, there had been a wide variety of blocks that could be edited into the inventory; over time, however, the game was updated so that these blocks became entirely unavailable, even though one utilized inventory editing. From Java Edition 1.13 onwards, blocks and items are completely different concepts, and numerical IDs no longer exist at all.

Currently, the game accepts only namespaced IDs (such as ) in most commands, and uses only these namespaced IDs when assigning blocks to the inventory and save files. The old method of obtaining a block via numerical IDs is no longer an option. In addition, the game automatically removes blocks with illegitimate namespaced IDs from the inventory, so using inventory editors is also no longer an option. Furthermore, certain blocks with both block and item forms, such as, cannot be obtained in their block form in the inventory; however, since the game has a corresponding item named  , the item form is given instead.

Despite never being intended to be obtainable, some of these could even be acquired in survival using unorthodox means - see Tutorials/Obtaining discontinued blocks and items for more info.

All such blocks
All of the following block items were removed at one point, as clarified in the following paragraphs.

In snapshot 13w37a for 1.7.2, the command was modified so that it would display the name of the item in chat. Due to this, 26 blocks were made unavailable.

In snapshot 14w25a for 1.8, changes were made to the way the icons of items were rendered, and the way block data was internally represented. Due to this, 12 blocks were made unavailable.

History of inventory appearances
As these were never intended to be implemented, it is possible to observe drastic and unexpected texture changes on these blocks due to minor code changes elsewhere from version to version.

Reverted potions
Before snapshot 15w31a for 1.9, potions had a form known as "reverted". In the inventory, reverted potions looked identical to their base potion, much like mundane and mundane (extended) potions, and their usage was also identical to their base potions, with the exception of turning into reverted potions rather than base potions. The only difference was the data values.

There were two general methods to create reverted potions, one of which involved the addition of fermented spider eyes. Reversion, in general, referenced changing a longer, upgraded potion into its original weaker potion (for example, changing from a potion of Poison (extended) into a potion of Harming (reverted) by adding fermented spider eye).
 * The first method involved adding glowstone dust (typically) to an already upgraded tertiary potion. Since these tertiary potions have already been modified with redstone dust (typically), they could be changed to their original (reverted) unmodified states depending on which modifier was added previously. Not all potions could be reverted (or react, for that matter) when glowstone dust or redstone dust was added to an upgraded tertiary potion (for example, adding redstone dust to an already extended potion did not yield a new potion).
 * The second method involved the addition of fermented spider eyes, followed by glowstone dust (usually). Method two worked by adding a fermented spider eye to an extended positive potion (i.e. an extended tertiary potion). In almost all cases, this would corrupt the potion and produce a negative potion of equal strength (in this case, extended). Then, glowstone dust (depending on the recipe) was added to the extended negative potion. Since these negative tertiary potions (regardless of origin) have already been modified with redstone dust, the addition of glowstone dust would revert the potion to a potion of lesser duration.

A good example of this process at work is the reversion of a potion of Weakness. A potion of Weakness can be made in two ways. The first method is by adding a fermented spider eye to a mundane potion (water bottle + ghast tear / glistering melon slice / blaze powder / magma cream / sugar / spider eye), then adding redstone dust to produce a potion of Weakness (extended). The second method is by adding a fermented spider eye to either a potion of Strength or a potion of Regeneration. Potions of Strength and Regeneration, in their base or extended forms, produce potions of Weakness with equal magnitude (for the sake of this example, fermented spider eye is added to a potion of Strength (extended) to produce a potion of Weakness (extended)).

Now, there should be two potions of Weakness (extended). Glowstone dust could be added to the potion of Weakness (extended), which reverted the potion into a base potion of Weakness. The act of reducing the duration from 4:00 to 1:30 was reversion.

Horse saddle


Horse saddles worked just like regular saddles, but for horses instead of pigs, which were added in the 13w16a snapshot. They could be crafted from 5 leather and 3 iron ingots. Horse saddles were removed in 13w18a.

Studded armor


Studded armor consisted of several sprites that were added in Indev 0.31 20091231-2. They were taken from Notch's unfinished game, Legend of the Chambered, along with other armor sprites. The sprites were added for testing purposes, didn't have armor health, and were eventually removed between Indev 0.31 20100204-1 and Indev 20100206.

Slowness Arrows
In Java Edition 1.10, slowness arrows dropped by strays contained a different NBT tag from slowness arrows crafted. The different NBT tag was fixed in 1.10.1.

Obtaining

Data-retaining minecarts
In Java Edition 1.10.2, when a minecart of any type was broken a specially named minecart was dropped. In this version, the game messed up when separating the minecart from the item inside, and accidentally let the minecart retain its previous data. The minecart obtained would be named entity.MinecartRidable.name, entity.TNTMinecart.name, entity.FurnaceMinecart.name, Minecart with Chest, entity.MinecartCommandBlock.name, entity.SpawnerMinecart.name, and Minecart with Hopper.

Obtaining:

File:Data retaining minecarts.mp4

Link to the bug report on the Minecraft bug tracker

Fish
Prior to Java Edition 1.13, the item now referred to as cod was simply known as fish, and had a generic texture strongly unlike the cod texture used currently. These were substituted out of the game in much the same way as roses.