Mobs are able to step up automatically while falling
in 1.8 when pushed by slime blocks (sideways) a entity is able to jump up over a one block gap and up by its automatic step up height
in 1.9 this has been increased to two blocks (shown in v=1VaMGOYdSX8&feature=youtu.be )
For most living entities (inc the player) this can jump up by half a block onto a half slab above,
however for Enderman and Horses this is increased to a whole block (again shown in v=1VaMGOYdSX8&feature=youtu.be )
Summary Table
The following table show how far vertically and horizontaly when pushed by slime blocks (sideways) a mob can move, Horizonally is measured as the air gap inbetween the blocks the entity move from and the block the entity moves to, and vertically is the number of blocks the entity can move upwards above the block the entity was pushed from, NOTE: none of the mobs where jumping at the time of testing (especially the player))
Mob | 1.8 Horizontal | 1.8 Vertical | 1.9+ Horizontal | 1.9+ Vertical |
---|---|---|---|---|
Player | 1 | 0.5 | 2 | 0.5 |
Villager | 1 | 0.5 | 2 | 0.5 |
Zombie | 1 | 0.5 | 2 | 0.5 |
Skelly | 1 | 0.5 | 2 | 0.5 |
Blaze | 1 | 0.5 | 2 | 0.5 |
Zombie Pigman | 1 | 0.5 | 2 | 0.5 |
Horse | 2 | 1 | 3 | 1 |
Enderman | 1 | 1 | 2 | 1 |
The way to fix this bug would be to disable the automatic step up code whist the entity is falling / not on the ground (like when flying in creative mode)
I'm sorry if this report don't make much sence it's a little hard to explain though 🙂
EDIT
This bug is not a Duplicate of MC-89030 as it can be shown in ' https://youtu.be/Wb0GfHunrRA ' to also affect 1.8.9 which is unaffected by MC-89030
EDIT 2
Added an world where you can automatally test if the bug still affect that version (called 'Bug test World.zip')
EDIT 3
Changed the bug report from only effecting enderman to affecting all living mobs, would like to thank panda for his help suggesting horses as another mob affected by the bug)
Related issues
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Also Affects 1.9.3 pre 3 (not sure how to add new affects versions) and also this bug didn't happen in 1.8.9 as the enderman fell in the 2 block gap
EDIT: I was later able to reproduce this bug in 1.8.9 so that part of this comment is incorrect

Click on the pencil next to affects versions.

Part of MC-89030, "pistons warp entities too much".

Bob - Thanks

[Mod] FVbico, MC-89030 only explains part of this not all, of it as there are 2 things which are going on here:
1: the mobs being pushed to far (Explained by MC-89030)
2: Mobs being pushed up a block (Not explained by MC-89030 as 1. the only nearby pistons are sideways facing and 2. the bug also occurs when you lengthen the slime blocks (make the slime blocks 11 long not 2 long) on so no pistons being nearby (badly explained, but this was used in a enderman farm spawn floors so imagine using it there.)
EDIT: Added screenshot
EDIT 2: Changed mc-89030 to MC-89030 so it links to MC-89030 properly

It may not cover all of this report, but it's nevertheless the same issue.
When MC-89030 is fixed, and this issue still occures, then this ticket will be reopened, no need to update affected versions until then.

I think the one block up part is because entities go up if they are in a solid block.

Most likely.

Ok then thanks bob and FVbico

Panda (reporter of MC-89030) said this issues is NOT a dupe of his bug (MC-89030) and surrested using the /entitydata command to test it so in did and this bug occurred again however often using commands can break things (like external tools can) so to prove this is not a dupe I tried to recreate this bug in 1.8.9 BEFORE MC-89030 was introduced proving these are 2 separate issues see 'https://youtu.be/Wb0GfHunrRA' for proof in 1.8.9 and 1.10 snapshot 15w21b
EDIT: Spelling and clarified about commands breaking things
EDIT 2: Changed mc-89030 to MC-89030 so it links to MC-89030 properly


Mob table in MS word as the bugs tracker seem to mess up the layout - Sorry
EDIT: Mob tables been fixed so I've removed the MS word document 🙂

Polar bears, Strays and husks (added in 1.10) also affected
EDIT: Polar bears, Strays and husks behave the same as the Player, Blaze, Cow, Zombie and Skelly's
EDIT 2: Spelling

Also Affects 1.10.2 (its not letting me update the affected versions though)

FYI: going on a holiday for a few weeks - therefore won't be updating this bug as I'll not have access to a PC so ill be unable to test any new versions of MC - sorry 😞

A friend tested this in 16w32a and the bug apparently still affects this version but I've not tested myself - added 16w32a to affected versions list (note: currently on holiday so may/will not be consistant with updating this bug)

affects 16w40a

Affects 16w42a + 16w41a

@unknown: no need to comment here about versions being affected. Since you're the owner of this ticket, you can just silently update it to reflect the versions that are affected.

Sorry, saw it on a lot of other bug reports and thought that what your meant to do, sorry
EDIT: Thanks for the advice though

My browser seems to be acting up so I also add a comment but minecraft 1.11.2 is also affected (let me know if its not so I can read it - thanks)

FYI: Due to current issues at work (having to work 60 hours a week and doing a training course for new equipment) , i will be unable to provide frequent updates on this bug report for a while (may be a year or two though) if someone wants to test the bug in the meantime please use the attached bug test world (open the world give the world 30 secs to perform the test and add the version tested with to the affected versions list), i will try to update the major release versions eg. 1.13.0, 1.14.0 ect but i can't make any gurentees.
If 1.13 breaks the command blocks in the bug test world ill try to get them updated, ive already got a working version in the snapshot 18w15a

cant add the affects version tag but affects mc version 1.16.1

Confirmed for 21w07a

cant add the affects version tag (nothing showing up in the select tag) but affects mc version 1.17.1

Can confirm in 1.19.4