Horses can glitch when moving up blocks

The truth is that I have seen this bug 1.14 snapshots for a while, before the pre-release 1 phase. But this only happens when you hold shift (to run) won't affect on the horse normally, which is why it is causing this glitch.

Riding on the horse without holding shift will not cause the glitch, as the horse will walk up on half blocks and full blocks normally.

Actually, my wife is not using shift and the horse glitches, and eventually both player and horse take damage.

While riding a horse up some stairs blocks, the console always spams "horse moved wrongly" lines.

Confirmed in 1.14 Pre-Release 2 and the following warning appear in the log :

Cheval moved wrongly!

.

I experienced this glitch as well with my horse and after I dismounted it, it instantly died for no reason. No mobs around, nothing to damage it. I assume maybe it compiled a ton of fall damage or suffocation damage as I was performing this glitch and then whenever I dismounted the horse it suddenly all registered?

Yes, this is an extremely annoying glitch and a big problem when riding horses on the worlds natural terrain. I tried to ride my horse because I was going to travel a while but the horse is useless with this glitch. 

I encountered this too. I found that if you look roughly 45° left or right you start moving again, and also if you stop and press forwards again. I have also uploaded a clip demonstrating this.

I also found my horse died when dismounting, luckily I found these reports before doing so and backed-up my save, tried it and sure enough the horse died 😞 I reloaded the backup and instead dismounted in water and the horse survived, so if you can do that.

Since MC-148340 was closed as a duplicate of this issue I'll re-post my comment with some minor edits here as I feel it's still relevant:

Looks like this is probably a duplicate of MC-100830. The issue is very similar and the same message gets spammed in the console, however, the issue is MUCH worse in the 1.14 pre-release versions than it was in prior released versions. Also, on some occasions the player can take (massive amounts of) (fall) damage from this, killing the player instantly.

MC-100830 doesn't mention it occuring with full blocks or slabs, but from my experience this has always been an issue with full blocks as well in prior versions, but has been less common to occur on full blocks, and most common on stairs.

If this is deemed not a duplicate of MC-100830, please add them as 'relates to' to each other?

Confirmed fixed in 1.14 pre-3

That still happens in 1.16.4, although more rarely, at least in the server version (Horse moved wrongly, that also results in a kick if allow-flight=false).