[MC-113809] Chorus Flower plant, Bamboo, Sugarcane, Cactus and other plants grow instantly when supporting block is replaced with same block type

The bug

For some plants when the block supporting it is instantly (e.g. using 0-ticks) replaced with the same block type the plant will grow.

The expected behavior is that the the plant should break, or that nothing special should happen.

As it currently stands this behavior allows for mass duplication of these items on the order of tens of thousands of items per hour. Far, far faster than any conventional farming method.

This bug may relate to MC-165023 where crop growth is randomly updated via falling sand on boats.

Affected plants

Carrots, Potatoes, Wheat, and Beetroot
Bamboo: https://www.youtube.com/watch?v=FROPCjl2DQM
Cactus: https://www.youtube.com/watch?v=NkV9iXii9_4
Chorus flower: https://www.youtube.com/watch?v=Ar0Zve-AzeU
Kelp: https://www.youtube.com/watch?v=Ctc6anMVPW4
Sugarcane: https://www.youtube.com/watch?v=qadaI38zRZc
Twisting vines: https://www.youtube.com/watch?v=ojiaUGdQmDk
Weeping vines: https://www.youtube.com/watch?v=VWbc8GNnkns

How to reproduce

Set the value for the gamerule randomTickSpeed to 0
```
/gamerule randomTickSpeed 0
```
Build a contraption like the one shown in

[media]

and activate it

Code analysis

Based on 1.13.1 decompiled using MCPConfig

The affected blocks check in their Block.updatePostPlacement(IBlockState, EnumFacing, IBlockState, IWorld, BlockPos, BlockPos) implementation (which is called when neighboring blocks change) whether they should break because the supporting block is missing. In this case a tick is scheduled. The problem is that when this tick is executed, the support block exists again and therefore instead of being broken, the plant grows (both actions are part of the update method Block#tick).

Linked issues

is duplicated by 5

MC-196383 0tick Ripener Fixed by Error Resolved

MC-157086 Bamboo duplication glitch with pistons Resolved

MC-160345 Sugar cane can instantly grow Resolved

MC-161508 Infinite SugarCane Glitch Resolved

MC-175689 Cactus, Sugarcane and Bamboo can be force-grown using the 'shaky sand' technique which is much faster than the now fixed 'zerotick' technique. Resolved

relates to 2

MC-165023 Sand dropped on boats can force update cacti, sugar cane, and bamboo causing them to grow very quickly Resolved

MC-124808 Blocks don't pop off when their support blocks are moved by pistons Resolved

Attachments

Comments 24

bemoty 2017-08-11T11:34:22Z

Can confirm for MC 1.12.1.

Jeremy 2018-02-10T08:48:36Z

This issue was fixed in 18w06a. It may have been fixed unintentionally though as some items (doors, item frames etc.) now do not break when moved by pushed slime blocks. If a mod could close this as resolved for now that would be great.

wobst.michael 2018-02-10T09:48:07Z

Resolving as fixed as requested. But keep an eye on it as things can change drastically until the 1.13 release.

Jeremy 2019-01-21T08:29:28Z

Upon further testing, this bug has not been fixed as of 1.13.2 or the 1.14 snapshots and should be reopened. It can work Chrous and Cactus as well. This can be seen in this video by ilmango which exploits this bug here: https://www.youtube.com/watch?v=NkV9iXii9_4

marcono1234 2019-01-26T21:39:25Z

Thank you for pointing that out. It looks like the given setup for the reproduction only works for chorus flowers. Do you have an easy one which works for cactus (as well) and could you add it to the description then please.

14 more comments

Phoenix616 2019-05-15T19:00:32Z

Still possible on 1.14.1 with this setup:

[media]

!https://i.imgur.com/gqlIYbkl.jpg!

Use the levers to start it. Might require some manual restarts until the timing is right and the middle sand block doesn't flicker anymore. Then place the cactus on top and watch it grow.

Jeremy 2019-06-13T18:35:38Z

Still an issue in 1.14.2 and 1.14.3 pre releases. This issue also affects sugarcane and bamboo plus other plants. This is really hurting server economies that run vanilla 1.14.2 or semi-vanilla. Please fix this mojang, it doesn't make sense and is overpowered.

Jeremy 2019-07-19T23:37:30Z

Still an issue in 1.14.4

Shane Martin 2019-08-09T13:07:41Z

Note: it also works on cactus by merely zero-tick plusing a piston beside the block you want to grow, to easily reproduce a zero tick condition all you need to do is put a button on the side of a piston and click it. The piston will start to extend, and pop the button off the piston which causes the piston to retract in the same tick.

http://prntscr.com/oqjdy0 You can just spam right click with buttons in hand and watch the cacti grow in the setup above

Tencryn 2019-09-27T13:52:04Z

I'm not sure what the current status on this is but I don't think a permanent fix is strictly necessary. A game rule that prevents 0-tick farms and is enabled by default is probably the better option. That way, it all comes down to the world owners as to whether or not they want to allow 0-tick farms. This is just my opinion though - it is still an exploit regardless.

Aaron Rhodes 2019-09-27T16:35:32Z

Exactly, it's an exploit, which means it needs to be fixed and not be accessible at all. People have a choice of whether to use them while they still exist, but that should not have any influence on how they are dealt with, nor should it remain a choice.

Fabrizio Cantero 2019-09-29T15:44:26Z

Yeah and it might cause some lag as well, right? 1.15 is a performance and bug-fix update, and I think this should be fixed. Also can confirm that it still in the latest snapshot.

[Mod] violine1101 2019-10-12T17:32:20Z

Regardless of whether or not you think this is an exploit or not, please keep the comments civil. We'll consider this an exploit until Mojang says otherwise.

Jeremy 2019-11-05T06:00:24Z

Added a link to the description of a new way to exploit this behavior. This method uses zero redstone but still force updates plant growth. This method might need its own separate ticket.

Bugreporty 2019-11-30T17:36:26Z

Another related bug: https://www.youtube.com/watch?v=PGJucW4j7t4

I really hope this is fixed before 1.15 comes out, but it might be too late for that now

Aaron Rhodes 2019-12-09T08:05:05Z

That is not how bugs are handled or treated (that much is basically common sense). There are many bugs that have been ongoing for years, that doesn't make them any less of a bug nor does it change the stance on fixing them.

mrfloris 2019-12-31T16:54:56Z

Useless argument to be honest to say that because they didn't fix it, it's not a bug. They're free to fix this in 1.15.2 if they choose to do so. They fixed the glitchy boat on sand to go even faster than zero tick, they can fix this as well.

Daniel DiFraia 2020-01-06T06:24:57Z

This whole glitch is actually better for servers than big auto farms. funny how a glitch helps the servers when the feature hurts them more

[Mod] violine1101 2020-01-06T10:10:59Z

This ticket remains open until Mojang either decides to fix it or to not fix it. Please do not use this comment section as a place for discussions. If you want to discuss this issue, feel free to create a post on our /r/Mojira subreddit.

Jeremy 2020-02-07T09:46:51Z

As of Snapshot 20w06a, this bug now also affects Weeping Vines and Kelp.

hutr2002 2020-03-15T03:11:26Z

It does not affect Carrots, Potatoes, Wheat and Beetroots.

Also it does not affect Bamboo Saplings.

It seems to affect those "stackable" blocks only. By saying "stackable" I mean blocks which can grow another one on top of itself.

Maybe it's an intentional behavior: when the supporting block is removed, the plants break one after another, having 1 gametick delay, rather than break all at once. Perhaps it's a kind of optimization.

Finnegan O'Donnell 2020-03-16T23:37:22Z

This shouldn't be patched, because the community loves it, and it would be like 17w49a, where pistons stopped leaving their blocks behind when given a one tick pulse, this would fix a bug, but devastate the community, and many people would wish for you to bring this feature back, because it costs more to set it up, and only gives you faster rates with certain plants, removing the need for massive, laggy farms just for getting quick rates with crops, the point is, this would upset the players, and shouldn't be patched. Anyways, what I'm saying is please don't remove this.

[Mod] violine1101 2020-03-17T00:26:24Z

As I already said above, this is not a discussion forum, please do not use the comment section for larger discussions. Feel free to create a post on our subreddit /r/Mojira or discuss this on our Discord server, though.

Edit: Someone created a reddit post, please use it for further discussion: Zero-Ticking should not be patched, and here's why

slicedlime 2020-03-17T09:10:37Z

Hi. I'm going to trash all comments on this issue from now on. We've already referred you to the subreddit for discussions. This is not a discussion forum.