Slime blocks moved by pistons often fail to bounce up the player

IMO, most likely caused by the fix of (and possibly a regression of) MC-88833.

Yeah, it definitely is caused by the (awesome!) recent changes to how pistons move entities.
I'm not sure where exactly this one is coming from yet, but I'm sure it can be resolved without backing off the previous fixes 🙂

Still confirmd in 15w38b & 15w39b

Confirmed in 15w39c (MC-89382)

15w39c Confirmd.

Confirmed for 15w42a - still not working
still not working correctly, works sometimes though
never got it working in the middle of grouped slime blocks

Confirmed in 15w45a. Even if it's wired to only push when you're on top of it (such as with a command block proximity detector), you only get pushed up about 25% of the time when walking over it. If you stand still on it, it works fine, but if you move, then it seems to depend on either your speed or the exact distance from the block before when it triggers.

Confirmed for 15w50a

it might be a no brainer, but also confirmed in 1.8.9

If you are moving - it 5/7 times fails
If server tps is lower then 20 - it fails.

every version is imporving the reliability

• confrimd for 16w06 - 1.9pre1 - 1.9pre2

Singleplayer is fine -multplayer its like 85 / 100 times now working
1.9pre3

moving seems to be more bugged then pre3
standing still 100/100

• confirmed 1.9pre4

https://twitter.com/SeargeDP/status/704383283061202945
"No code changes between 1.9pre4 and 1.9"- SeargeDP
so, still confirmd 1.9 :/

Slime blocks still only occasionally launch the player in 1.9.2. Maybe about a third of all times for me.

Also, whether it works or not seems to somehow be tied to the game's performance. I tried it on another, better computer and slime blocks definitely launched me more often, maybe about 80% of the time. Anyway, that may be why people get different probabilities.

@Jelmer
I got fiberglass internet, and a super beafy server; and in multiplayer is more stable then single player on my laptop (when on lan)
so it's all relative
(Desktop is other way around)

I came here to report this and found this already existing report.
I never had issues before, but since 1.9 came out all my jump pads broke.

To add to my previous comment, I made two very interesting observations that may be helpful.

1) Whether the player is launched or not seems to not only be related to the performance, but to the frame rate itself. Now that sounds ridiculous and it probably shouldn't work like that, but I tested it several times by limiting the frame rate. At 10 FPS and probably lower successful launching rarely happens, above maybe 30 or 40 FPS it seems to succeed almost every time. All in all however it seems more reliable than it was in 1.9.

2) Other entities (tested with items and creepers) seem to be correctly launched every single time, even at a frame rate of 10 FPS.

@unknown Does lowering the FPS in SP give any constraints to the TPS of the internal server as well? I assume it does, so your observations would be in agreement with that. If not though, that would certainly be strange.

Apparently it does, but I'm pretty sure it shouldn't.

Confirmed for 1.12.1

Confirmed for 1.13.1.

This seems to have gotten way worse since the latest 1.14 snapshots. Now if a player is moving on them while the piston is extending, he almost never gets launched up.

Since 1.13 I never got up while moving
No worse or better experience for me

Got a lot worse in the official 1.14 release.

This is still a problem in 1.14.2 Pre-Release 2

This is still a huge problem in 1.14.4. Please fix this bug, it's so annoying for us redstoners

Significantly worse on 1.14.4 to the point of making slime block bounce mechanisms entirely unusable. Bounces almost never work on the first attempt now, and I've had periods of upwards of a minute of constant triggering where the block will never cause a bounce.

The cause of the bug seems to be moving whilst the slime block moves. If I stand perfectly still the bounce will work almost every time, but walking or falling as it moves causes it to fail to have any effect.

Confirmed in 1.15.

Seems to be related to movement of the player, as mentioned above, but occurs sporadically. I've been able to successfully chain upwards of 20 bounces while sprinting in a row, yet at other times I can't even manage a single one.

This should be noticeably better in 20w07a, however it can still fail if the player falls onto the moving slime block because of MC-123217.

This is also a problem in Bedrock edition...

Issue seems to have reoccurred as of 1.20.3 but only when the player is in a boat.

• It doesn't effect other mobs in boats

• happens when moving or at a standstill as long as player is in it.

• Did not see any problems with launching myself on slimeblocks only when in a boat.

There was another post on this specifically but it was linked to this one as a duplicate so I'm commenting here.

Hope this is clear let me know if more info would be helpful