When climbing up blocks while riding a horse, the horse occasionally glitches slightly (it gets reset backwards by the server), and the "Horse moved wrongly!" warning is logged in the server console (or game log in singleplayer).
In particular, this happens almost always when walking up stairs with horses, although it doesn't appear to happen with slabs. However, this issue has also been reported to occasionally happen if there are no stairs involved (e.g. MC-147523).
Steps to Reproduce
Summon a moderately fast horse, e.g. by using the command provided below.
/summon minecraft:horse ~ ~ ~ {attributes:[{id:"minecraft:generic.movement_speed",base:0.35d}],Tame:1b,SaddleItem:{count:1,id:"minecraft:saddle"}}
Mount the horse and climb up stairs with it.
As you do this, pay close attention to the horse's movement and frequently check the server console / game log.
Expected behaviour
The horse can properly walk up the stairs.
Actual behaviour
The horse is very slow walking up the stairs; additionally in the server console / game log, warnings of the following format are sent:
Horse (vehicle of <user>) moved wrongly! 0.5
Notes
This is a new problem since the 1.9 update, and it happens with all horses, no matter their speed.
This also affects other entities than horses, however it appears most frequently with horses in regular gameplay. For example, camels with Speed II are also affected by this when sprinting, and so are pigs with Speed V.
Linked issues
is duplicated by 8
relates to 2
Attachments
Comments 64
can confirm
This is not just error logs. It manifests in game with a graphical glitch and more importantly slows down your horse. It also effects Pc.
Same graphical glitch on PC running JRE_1.8.0_66 on Windows 7 pro x64 En.
AMD Radeon HD 6800 Series with Catalyst Version 15.7.1
The problem do not seems to happen when running down the stairs or running perpendicularly.

This is what it looks like for me. No problems when going up slopes of one block without the stairs
Can confirm in 1.21, horses still glitch out a lot while climbing stairs

This seems to be fixed in 24w45a. Can somebody else confirm?

I also cannot reproduce this in 24w45a.

Is this the issue demonstrated here?: https://youtu.be/r2l2VUNMvwI?t=9m

Has been fixed by 24w45a. I am able to reproduce in 24w44a, as per screenshot of the log output. (24w44a.jpg)
Confirmed. I will also mention that I have started taking the same measures to avoid the glitch