Pre-release 2 has been released, please go to the pre2 known bugs page to report bugs on it!
Use the Discussion page first before editing any onto this page. Bugs can be confirmed by checking into the discussion page and make sure other people reply to your report and have the same problem.
This page is for new bugs found in Beta 1.9pre, any bugs found in 1.9 that exist in older versions will be deleted.
Bug Labels: Major bugs will be labeled with [!] before it. Bugs that can crash Minecraft or a server will be labeled with [!!] before it. Minor bugs reports will be labeled with [X] before it. Possible bugs/features that you and the community (on the discussion page) are unsure about will be labeled with [?] before on this page.
- A border into a Swamp Biome displays a harsh change in color with grass, tree, vine, and water unlike normal Biome borders.
- Water color underground (even at level 5 Bedrock) is still affected if the cavern is beneath a Swamp Biome.
- Lava touching water may sometimes create a Sandstone block. 
- Snowfall generating snow on the ground can destroy redstone, torches, rails, etc.
- Torches cannot be placed on top of Netherrack Fences.
- Stair shadows are to dark
- For some players, creating a new map will stop the process and the game will say "Switching Level", and shortly after closes Minecraft.
- For some players, generating new chunks in a pre-1.9 world will crash the game, leaving no saved data.
- For some players, clicking the "video settings" button will freeze the game on a black screen.
- The Gold Nugget is unlabeled in the creative mode inventory, which is located to the right of the Ghast Tear.
- Mycelium, Lily Pads and Nether Brick Stairs are not shown in the creative mode inventory.
- [?] Lily Pads appear to show a light gray texture when viewed in your inventory.
- For new maps, the MB size in the world file under the Singleplayer menu will not change, it will stay at 0 MB. For existing worlds, the size in MB will not change when exploring new areas.
- Sometimes when a new Survival or Creative map is created you will spawn in a previous Creative or Survival save, complete with any buildings you have made. This may happen even if the file had been deleted prior to the new world being loaded. 
- Placing a torch or redstone torch on snow when there is an adjacent block will cause the torch to be placed on the adjacent block (see picture). Only happens when the adjacent block is one which can normally have a torch on it (e.g. stone and not glass). Oddly, they also attach to note blocks.
- Pressing Shift twice quickly while walking forward will cause you to sprint which was said to be disabled in the next update (v1.9).
- Occasionally, naturally spawned torches will not illuminate properly.
- Glowstone does not self-illuminate properly; i.e. a block of Glowstone encased in glass appears nearly black.
- Cave Spiders do not inflict damage to the player.
- Snow Golems will not leave a trail of snow on Mycelium blocks. Snow Golems will leave snow trails only on trees in a Swamp Biome, no other tree.
- [?] Snow Golems can be created underwater.
- [?] Snow Golems take no falling damage.
- [?] Snow Golems will not melt/die when arriving/created in a warmer Biome (such as a Desert). Snow Golems were said to melt when in the presence of a warm Biome. Snow Golems can be created and will not melt when made in the Nether, which should not be possible as water will evaporate when used in the Nether.
- [?] Snow Golems cannot be created mechanically (For example: A piston moves a Pumpkin block onto two blocks of snow yet the mob will not spawn).
- Shearing a Mooshroom results in a duplicate client-side Cow visible only to the shearer.
- Mobs can spawn from Monster Spawners even when Monsters = False.
- Excessive lag on new or existing worlds, even if new chunks are not being created and all graphical settings are set to Fast/Off. The lag is much worse on single-core CPUs, possibly due to the threading of chunk saving/loading.
- For some Windows users a possible fix for this lag (or a reduce in lag) is to set "javaw.exe" to High Priority in the Task Manager under the processes tab. Seeing how this method affects the smoothness of the game, this is confirmed to be a memory leak.
- Chests will not produce any sound when opening or closing.
- Endermen, Snow Golems, Blazes, Magma Cubes, Villagers and Silverfish do not produce any sounds.