Player crouches with a delay

Did some testing and there is a reproducible 0.2 second (4 tick) delay between the player pressing the crouch button and the character sneaking

Can confirm. This is easily noticed while spamming the sneak button. It just doesn't have the same effect anymore.

Confirmed. Amount of delay varies, but is usually quite long and noticeable.

Confirmed.

I just found out what the technical reason is for this. The client does not update its own metadata when the player starts/stops sneaking. The metadata has to be updated by the server. Only after the metadata has been updated, the client displays the animation (and activates part of the functionality). The delay is caused by network delay and due to the server updating the metadata not until the next tick.

I guess the responsible developer will probably be aware of this, but I wanted to mention it anyway. Maybe it helps 🙂

FYI: I noticed this, because I wasn't updating the clients own metadata on my custom server software at all. This worked fine in versions prior to 19w14a (or at least in 1.13.2), but in 19w14b sneaking wasn't working at all. After removing the check for not updating the clients own metadata, the issue vanished (though sneaking is obviously still delayed).

can reproduce in 1.14 pre-release 1

The delay is shorter, but still around 2, sometimes 3 ticks (and will be much worse on servers with just a little bit of lag), even in singleplayer on a flat world (= without much going on). Also, why check for people STARTING to sneak in the server? Wouldn't only checking the unsneak be sufficient to prevent any client abuse?

Can confirm, it still happens in 1.14 Pre1.

I can also confirm that the delay is still noticable in 1.14 pre release 1. 

(Un)Sneaking should not be handled serverside. If serverside checking is really necessary, the initial check should still be performed by the client and then can be corrected by the server. This does guarantee low latency in all cases that were checked correctly by the client. If the clients check fails unsneaking will be a bit weird, but it will end up in a correct state after the server updates it. 

Still confirm that it's still around in 1.14 pre-release 1. And I'll be honest- I haven't hated something in an update more, makes building in creative and with command blocks super frustrating. 

Confirmed that this is still a major issue in 1.14 pre-1. In the worst case, depending on lag, it can take several seconds until the player starts to sneak.

There are still some top priority glitches in 1.14 Pre-Release 1 that need to be fixed. This glitch is no exception (but less of a priority than the chunk loading one known as MC-138114); countless players will die from falling off cliffs, into lava, or into any other dangerous situation thanks to this (even if they don't lag). If they don't fix these game breaking bugs, many players will complain and possibly won't update to 1.14.

Still in pre release 2 

Delay WAS more or less resolved in pre-1 but it was still there.

Confirmed for Prerelease 2

Is this still an issue in 1.13 pre-3?

only one way to find out

Fixed for 1.14-pre3. May pop up in future pre-releases though.

I doubt that. Also can confirm that sneaking now works properly in 1.14 Pre-Release 3