Similar to Dwarf Fortress, Minecraft's status as a Perpetual Beta that continues to receive updates for over a decade straight, in conjunction with the many peculiar interactions one can have in the game's world, makes Good Bad Bugs inevitable. The previous versions, especially those released prior to Minecraft's final release, had even more examples of such.
- Like Dwarf Fortress, the strange interactions of Minecraft's world create a lot of these: Swimming up waterfalls? Teleportation via minecarts? Sand-on-torch floodgates? Glitch after glitch has been discovered, explored, and developed by the massive Minecraftian community, before being turned into yet another incredible, important, and intriguing tool for future players. They've started fixing them now, much to the dismay of players who can now drown in a small waterfall.
- Mobs used to be unable to see through glass, treating it as a solid object until they could 'see' you at least once, following which they would be able to detect you through any block.
- A (now patched) glitch let you duplicate items by storing an item inside a chest, then closing the chest while still dragging the item, causing a dupe item to drop in front of you. Although the duped item would disappear if the player attempted to use or stack it, it could still be used to craft, making mass production of iron or diamonds a reality.
- Another glitch allowed players to speed up minecarts by placing another on a separate track and running past each other. The booster cart glitch, which allowed minecarts to speed up considerably, had an entire subway system founded on it. Again, the creators recognized that this bug was much more popular than the legitimate Powered Minecarts, which led to the official introduction of Powered Rails before the glitch was removed. Notch, one of the game developers, didn't get rid of them in a timely fashion, but added in a replacement feature (powered rails) that works without any glitches, albeit differently. He then proceeded to remove the glitch boosters in the next patch, along with boat elevators and rapid-ascent water ladders, to the dismay of the community. In an attempt to make powered minecarts work again, the glitch (albeit weaker, but still useful) was reintroduced. Notch and Jeb just can't win.
- Speaking of rails: a glitch — still unfixed as of 2021 — lets players build a contraption of sticky pistons and slime blocks that duplicates rails by exploiting the rail mechanics. Make one on top of hoppers sending everything to a chest and come back a half-hour later to stacks upon stacks of rails. This works for all four types of rail, so if you're building a lot of minecart railways, you'll be saving yourself truckloads of gold and redstone (and if you don't have access to abandoned mineshafts, iron) by having a set of ever-replenishing chests of rails.
- If a multiplayer server is experiencing significant lag, you can see flying squids. More importantly, if it lags enough that it doesn't generate the terrain quickly enough, it can let you see underground. A split second is all it takes to see hidden mineshafts and structures.
- Normally, sand and gravel blocks will be subject to gravity (the only two naturally generating blocks in the game that are) and fall down if you remove the block supporting them. However, due to the way the game world is generated, you can end up with floating sand/gravel blocks. If you place a block next to one of these, the physics engine will recalculate the floating blocks, which can result in large areas of apparently solid land suddenly caving in and collapsing. If done right, you can use this to make pitfall traps, or just make cool floating structures that shouldn't be possible.
- Placing sand/gravel on top of a 2-tall plant such as a rose bush or sunflower, then breaking the bottom of the plant allows one to create floating sand/gravel anywhere they wanted. This was amazing for traps; it was even reinstated intentionally after being fixed since it was so useful.
- Prior to Beta 1.8, using "404" as a world generation seed would create a gravel patch in this manner; upon destroying one of the gravel blocks, the sand and gravel in a rather large area would spontaneously collapse and reveal a giant sinkhole from sea level to near-bedrock. Various players had thus participated in the "404 Challenge", which involved surviving in the sinkhole with (among other limitations) no torches.
- While not strictly a glitch, the water physics in Minecraft are very peculiar and players have found all sorts of inventive ways to exploit this to their advantage. People frequently abuse the game's bizarre water mechanics for the sake of comedy. They just got more bizarre and water now resembles a gel-like substance in consistency. Place a good heap of TNT on an island and you can blow a hole in the ocean.
- As an example, this water elevator
which abuses water flowing in a certain direction in a certain way. Add a pool of water that negates falling damage at the bottom, and you've got the fastest elevator system possible. - What else is good with water? Boats? The feature that's really hard to control and breaks into a smaller fraction of the pieces needed to make it at the drop of a hat? The annoying vehicle that glitches out and ejects you several blocks away from where you should be upon dismounting? Actually, they are pretty good. Mojang finally heard the pleas of the fanbase and started fixing boats in Minecraft 1.9. Now they are nowhere near as annoying. But one snapshot (specifically 16w04a) went so far as to accidentally make boats rideable on land — at the exact speed with which they would travel in water. That's right. As of that snapshot, Minecraft boats act almost exactly like Minecraft cars! However, this glitch was later fixed.
- As an example, this water elevator
- A glitch fixed in 13w47a allowed the player to duplicate any object they could place in a flowerpot, by destroying or moving the block below the flower pot. The use of redstone could turn this into dye factories or semi-automatic tree farms.
- The now defunct "bury yourself in sand and see all the caves" bug. You can still bury yourself in TNT, as well as a few other blocks.
- A way to do this without hurting yourself is to use a piston for force yourself into a crawling position inside of a composter.
- Multiplayer had Chunk Errors, now fixed.
- In the alpha version of multiplayer, you could toss away your about-to-break tool and pick it back up to fully mend it (fixed in beta).
- Burnable blocks set on fire sometimes never burn down, especially if boxed in when lit, allowing for eternal flames and always-lit fireplaces. This was fixed in Beta 1.3. Now, it's a feature—Netherrack and soul sand are two blocks that create eternal flames when lit, with the former lighting normal fire and the latter creating blue soul fire.
- Sometimes after crashes, parts of old saves are left around, and you can come across parts of your old builds in a supposedly fresh world.
- Fishing poles could be stacked, unlike any other item limited by durability. If you equipped and used a stack of fishing poles, they'd all lose durability at the same time. If you dropped one fishing pole on another, the resulting stack retained the latter's durability. This could be exploited for infinite fishing. The ability to stack them was removed in Beta 1.6, effectively removing the exploit. Luckily fishing rods with the Mending enchantment are easy to find and fishing gives you experience, so infinite fishing is no longer a problem.
- Set your system time ahead by an hour while playing. You'll find yourself digging faster than the Flash on caffeine bullet time. This glitch was fixed in Beta 1.6.
- The Duplication Glitch in 1.2.5. You could easily double the amount of resources on hand by this trick. Of course, it was patched soon after. Duplication was also possible in the PS Vita edition if you had a Playstation 3 as well. Namely, when you saved in the Vita edition, the world was saved, but your character placement and inventory weren't. By uploading your save and making your inventory on the 3 be a bunch of rare materials, you could then place them all in treasure chests on the Vita, save, then exit. When you reload the world, all the materials are both in the chest and your inventory!
- This can still be done by first copying the level.dat file from your save folder and putting it in a separate location, then putting your items in a chest and leaving the game. Put the level.dat copy back into the save folder, replacing the old one, and reenter the game. Your items will now be in the chest and your inventory.
- The Far Lands, caused by traveling too far into the distance of an infinite map, in which you'll end up in strange geometric landscapes. Notch has stated that this is one he won't fix because he thinks it'd be cool to have a strange faraway land. Sadly, though, they didn't survive the Beta 1.8 update due to the rehaul of the map generator accidentally fixing the bug that created them. The Far Lands are so infamous they managed to get referenced in Super Smash Bros. Ultimate, in which Steve's Classic Mode route is known as "The Journey to the Far Lands".
- There was one exploitable glitch that allowed players to climb ladders normally even if they were spaced every other block, thus allowing people to conserve building materials. The game's creators recognized how popular this practice was, so at the same time that the bug was fixed in Beta 1.5, the ladder resource cost was cut in half.
- A bug involving pistons and redstone repeaters has the capability to produce infinite amounts of blocks. Including diamond blocks. See in action here. Fixed in the 1.7.3 patch.
- Sometimes, when the game crashes, some blocks will be glitched in or out of existence.
- An update to the Endermen improved their AI; specifically, if they come into contact with water, they would teleport away from it to avoid getting hurt. The glitch happens when it's raining, causing an Enderman to rapidly teleport around in an attempt to keep itself dry. Now, imagine being out during a rainstorm, and you see an Enderman for a split second out of the corner of your eye. You're almost certain it's around, you just don't know where it is. It could teleport into your line of sight, and then the real fun can start...
- There was a bug that causes water and lava flow to transform redstone wire into obsidian blocks. The practical upshot is that you only need one lava source block (which cannot be replenished like water can) to create as much obsidian as you need, versus the traditional method of permanently turning the few lava source blocks you'll find into obsidian. There is still a resource cost in the form of redstone dust which is semi-finite, but is far more abundant than lava (a single block of redstone ore yields 4-5 redstone dust, which can be increased to up to 8 with Fortune III, each of which can be converted into obsidian, and it's easy to find enough redstone ore to make hundreds of blocks of obsidian rather than a few dozen which you would get from converting the few lava source blocks that you'd find). Plus, redstone is a level 2 trade from a Cleric villager; you can get 1-4 redstone dust for a single emerald, so if you can grow enough Farmer villager trading fodder to get a steady supply of emeralds, you can get pretty much an infinite amount of redstone to use for this bug. So this would have been renewable, if it wasn't fixed in 1.8. Fortunately, 1.17 was released later, which makes lava a balanced renewable resource by using a slow dripstone and cauldron process.
- The first 1.10 snapshot brought about some nice things, but perhaps one of the best things seen was Savanna villages spontaneously combusting.explanation
- Bedrock can actually be broken, with a bit of finagling. Doing so to breach a hole in the ceiling of the Nether gives you a wide, expansive, flat-grounded, mob-free space that's perfect for building structures, establishing travel routes quickly, or setting up Pigman farms.
- It's also possible to this with an ender pearl by pointing it at a very exact spot (usually the corner of the Bedrock block) though this runs the risk of you suffocating to death.
- For consoles: it's possible to escape the Battle Mode lobby and explore the surrounding area. Turns out the structure is built on an elevated piece of land above a Superflat map. Travel far enough and you can find villages.
- If you put a Nether Brick fence between two wooden fences, it won't connect to them, but mobs still can't get around them.note This makes them a more convenient alternative to fence gates for farms/ranches since you can go in and out of them with ease without worrying about accidentally letting out any of your livestock.
- As of Snapshot 18w10c, Slab + Sticky Piston + Water Bucket = Pushable/Pullable Water Source Block. Combined with the improved water mechanics, especially those of Magma Blocks and Soul Sand, this could've opened up a new (albeit rather dangerous and tricky, since flowing water washes off redstone) world of possibilities with redstone creations if it hadn't been fixed rather quickly, in 18w21a.
- While swimming, you can move horizontally through one-block gaps. You can do this as long as you have water to swim in when you enter the gap — taking away the water allows you to essentially "crawl" through small spaces, which is actually fairly useful.
- Eventually became an Ascended Glitch in the Java version as the "suffocation prevention" (as the official Wikia calls) when Henrik Kniberg, one of the programmers at Mojang, made a Tweet showcasing that a piston that pushes a block on top of the player's head will achieve the same effect as the bug above.
- This can also be achieved with a trapdoor. Make a 2-block tall gap, place a trapdoor, open it, walk to it, and then close the trapdoor and you will achieve the same "crawl" effect.
- Eventually became an Ascended Glitch in the Java version as the "suffocation prevention" (as the official Wikia calls) when Henrik Kniberg
- Advanced Redstone on the Java version is built pretty much entirely on this trope.
- Quasi-connectivity, which is the strange bug that redstone dust two blocks above a piston will power it, even though they may not be touching. The thing is, the piston wouldn't change its extended/retracted status until a directly adjacent block was updated, whether removed or modified. Thus led to the creation of Block Update Detectors, which were extremely useful for making invisible redstone inputs. The Observer block added later is, essentially, an official implementation of this feature.
- Powering a sticky piston with a pulse that only lasts one tick causes it to push out whatever it's holding, but without retracting it. This feature is used predominantly to make flying machines and 1-bit memory circuits.
- Redstone wire placed on transparent blocks such as top slabs or glass will transmit signals upwards, but not downards. This allows for easy and delay-less one-way signal transmission.
- A weird bug involving feeding pistons a redstone input of duration less than 1 tick causes sugar cane, bamboo, and other certain types of plants to grow. Dubbed "zero ticking", it has been used to create machines that spew large quantities of farm materials, faster than any reasonable glitchless solution.
- The dubbed "Trident Killer" exclusively on Bedrock edition is result of one. In Bedrock edition, there's a bug where a thrown trident can still inflict damage upon being moved and does not lose durability through that, and mobs killed by it drops EXP as if they are killed manually. As a result, thrown tridents, through use of perpetually moving pistons are used to automatically kill mobs in mob farms while still gaining EXP while on AFK. However, this could be a case of Purposely Overpowered as mob farms in Bedrock are generally less efficient than in Java due to difference of mob spawning rules.
- Axolotls move faster when attached to a lead. This was probably to make sure they didn't get so far behind they broke the lead, since they move very slow on land. However, it's amusing to watch them literally run circles around you.
- A rather short lived one in Bedrock edition 1.17 is a glitch where a dripstone under a block which is under a water source could full a partially filled potion cauldron, which allows to duplicate potions without the need to brew a new one. This was fixed later a few minor updates later.
- Another short lived one in Bedrock, but a potential candidate for the most hilarious bug ever introduced to Minecraft, was frogs eating goats. Apparently a testing leftover that developers forgot to remove, this is just absurd.
- Like all smaller objects, wooden signs mounted on block faces are treated by the game as taking up a full block's worth of space while having a very small hitbox. Two notable techniques allow you to exploit this to create hidden or interesting passages.
- If you hang a painting on a wall, then very quickly destroy the edge blocks it's on and put wooden signs on the inner faces where the blocks were before the painting drops, the painting will remain hung on the wall, now attached to the "blocks" the wooden signs occupy. Since the paintings have no collision, this allows you to hang them over a passage and walk right through them for secret entrances. The technique has become beloved and well-known enough to be cliche in the community now, and most experienced players will likely make a beeline for any painting in a player's base because of it.
- Wooden signs can also be placed on the inner rim of a 2-block wide opening in a ceiling. Lava and water will spread out across the signs while not falling into the room below, allowing you to create water or lava ceilings to rooms while keeping the rooms dry. Stacking signs on each other allows you to make a larger spread of lava and water, though the signs make the ceiling less open.
- It is typical for many servers to have a Nether ice subway system which connects player bases to other important objects. This is possible because a boat moves on ice with insane speed, and because ice does not melt in the Nether.
- Zombies can break down doors on hard mode... unless you place the doors on sideways in a way that means the door is, according to the game, "closed" when it is actually open. Since zombies are coded to just go through open doorways, they'll run against the "open" door that is actually blocking their path, effectively creating a zombie-proof door.
- Wardens can be "tamed" by placing a trapdoor between two Sculk sensors in a way that the two sensors are repeatedly triggering the trapdoor to open and close. Because of this, the Warden will simply walk over and stare at it, ignoring all other sounds, unless you are stupid enough to touch or hit it.
- Under the right conditions, it is possible for a TNT to "trigger" in a way that creates a primed TNT entity but leaves the TNT block intact, effectively duplicating it. This allows for the creation of machines that can destroy blocks directly, such as fully automatic cobblestone generators and worldeaters to clear huge amounts of terrain in a short time.
