MC-3155Piston remains powered without redstone
1 of 2 pistons remained active after all redstone wire and lamps and pistons and all other blocks around it were destroyed. I replicated this bug several times.
What I expected to happen was...:
Once the restone wire above the pistons lost power, I expected both pistons to retract
What actually happened was...:
After cutting power to the redston wire, 1 of the 2 pistons remained powered
Steps to Reproduce:
1. In the "Before" image, everything works just fine
2. In the "After" image, the piston remains active
3. In the "Bug" image, all blocks around the active piston have been destroyed. You can also see in the background that I replicated the bug with both types of piston.
Now, this was in creative mode, but I feel it is worth mentioning that when I switched over to survival mode I was able to again replicate the bug with one exception. Upon destroying an adjacent block, (after destroying all redston) the piston DID retract.
Environment
Windows 7
Linked Issues
Created Issue:
Piston remains powered without redstone
1 of 2 pistons remained active after all redstone wire and lamps and pistons and all other blocks around it were destroyed. I replicated this bug several times.
What I expected to happen was...:
Once the restone wire above the pistons lost power, I expected both pistons to retractWhat actually happened was...:
After cutting power to the redston wire, 1 of the 2 pistons remained poweredSteps to Reproduce:
1. In the "Before" image, everything works just fine
2. In the "After" image, the piston remains active
3. In the "Bug" image, all blocks around the active piston have been destroyed. You can also see in the background that I replicated the bug with both types of piston.Now, this was in creative mode, but I feel it is worth mentioning that when I switched over to survival mode I was able to again replicate the bug with one exception. Upon destroying an adjacent block, (after destroying all redston) the piston DID retract.
Environment
Windows 7
Linked Issues
duplicates1
TRASH-991
Attachments3
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Duplicate of: MC-3155 - Please use the search function to see if your bug has already been submitted.
Currently 30% of tickets are being closed as duplicate.
according to my observation, pistons, sticky pistons, dispensers and droppers can be activated by applying Redstone signal to the space above it; so if there's a Redstone block/charged block/Redstone torch etc two block above it with air in between, the (sticky)piston/dispenser/dropper will activate remotely and deactivate once the signal is removed, but only when the block adjacent to it is changed.
I don't know a lot about the technical stuff here but I think this is due to some 'update'(possibly block or chunk update), which is triggered by the block space adjacent to the piston/dispenser/dropper changing(placing/destroying etc.), which, combined with space above's 'conduction' caused the remotely-activating-and-non-retracting piston; the dispenser/dropper are impulse-type blocks, so they only show remote activation.
in the examples below, most blocks activated by placement of a signal source adjacent to the air above said block/'updating' said block by destroying block next to it after placing signal source, and deactivate by 'updating' the block (by placing blocks next to it) after removing signal source. most signal sources are block, so their placement themselves will bring the 'update'(see the text example below); the button is a special case, as it doesn't have any signal on placement, so I used a second piston to simultaneously change the space next to target piston(in this case, place a piston head in it), thus 'updating' it while giving power to the air above it, so it activated as expected.
these two bugs/unintended features((sticky)pistons/dispensers/droppers powered through air above & needs 'update' to activate/deactivate) can explain a lot of issues here(such as placing a redstone block on top of top-facing piston causing the piston not retracting; removing the redstone block give the piston 'update'(because the block is adjacent to its head) so it will retract.):
This is used in Block Update Detectors (BUD-switches) and is some kind of bug turned into a feature.
Whether this will be fixed or not depends on the redstone changes currently planned for 1.5.
As Mustek said this is currently considered a feature and not a bug. In short: A piston is able to receive power from 2 blocks away. But it is updated only if something 1 block away changes. I know this can be very confusing. I think this report should be closed in favor of other reports.
Duplicate of
MC-108.