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MC-171969

Fall damage is negated when stepping up after falling

Players can negate all fall damage if stepping up something as they land. This behavior is reliably reproduced and is not random, though getting the correct distance/relative position and orientation between the starting coordinate and the coordinate where the stepping up + landing are meant to happen is vital.

While the landing sound plays after the fall, no damage is taken, and no damage sound is heard (meaning the client hits the ground, but the server does not damage it).

In multiplayer, no falling sound is heard when someone does it next to you. Instead, the landing is smooth (no bobbing up) and slient.

From a discussion in comments, it seems this was introduced at the same time as the fix for MC-153698.

What is not new is situations where the player steps up higher than they are supposed to (image, and stepping up whole blocks in the video). Only the fall damage negation is.

What I expected to happen was...:
...not to step up the block in the video, and to take fall damage.

What actually happened was...:
...I stepped up the block, and took no damage.

Steps to Reproduce:
1. Place a block on flat ground
2. Leave a gap of 3 (air) next to that block
3. Pillar up 8 blocks
4. Walk fairly perpendicularly towards the gap from the pillar, and keep holding the forwards key (no sprinting).

 

Related but not directly (here, the issue is just the application of fall damage, not the stepping up), is the image which shows a setup where you can start on the slab, sprint jump into the chest (thereby slamming yourself against it), hold forwards, and step up the chest.

 

Thanks for reading. 🙂

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Affects 20w06a and 20w07a. I have added a video, which shows how this bug can occur in normal gameplay - when falling onto the edge of a block.

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From my testing, this bug has debuted in 1.15 pre-release 5. It is likely that the fix for MC-153698, which caused players to take fall damage when jumping on a boat, has introduced this bug.

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I doubt the boat fix is its origin. Afaik it was due to the server accumulating player falling speed (as if the boat was not blocking the player from falling, and the player was teleported back up to their correct position, albeit without losing speed, every tick), while the client didn't.

It's possible, but that would imply that it would be related via something about player velocity, and that stepping up negates the accumulated falling speed. I doubt that stepping up things is done via velocity changes.
We may then think of a scenario where it's done by some form of teleportation, meaning that such teleportations reset the falling velocity, which feels like an odd fix to the boat thing (why fix the speed part instead of the client/server desync ?)

Thanks for the speculation 🙂

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I agree that there doesn't seem to be a correlation between the fix of that bug and the introduction of this bug. However, only 11 bugs were fixed in 1.15 pre-release 5, and the boat bug seems the most likely candidate to me. What change do you think has introduced this bug?

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I have just taken a look at all the announced 1.15.x changes. The boat change does indeed seem most likely, good guess !

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Ah, okay! Thanks! 🙂 Can you also confirm the bug not being in 1.15 pre-4, but in pre-5 and above? 

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Confirmed (procedure described above in a random new survival world) :
Stepping up, fall damage in pre-4
Stepping up, no fall damage in pre-5

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Good to know. I guess me asking Slicedlime for a fix for the boat glitch in 1.15 has caused an even more prevalent issue 😛

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Affects 20w09a.

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i used to use this to jump off mountains

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mgatland

Confirmed

fall-damage

1.15.2, 20w06a, 20w07a, 20w09a, 20w13b, ..., 20w19a, 20w20a, 20w21a, 20w22a, 1.16 Pre-release 2

1.16 Pre-release 3

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