mojira.dev
MC-110236

Hoppers do not always transfer items when unpowered

The bug

A chain of hoppers will not transfer items consistently if the hoppers below them become unpowered. Often, one hopper will not transfer items but the others will. This was working in 1.10.

How to reproduce

  1. Place a line of containers between eight and 15 blocks long:

    [media]
  2. Place a hopper above each of these containers feeding into them.

    [media]
  3. Place a line of solid blocks one block behind and one block above these hoppers.

    [media]
  4. Place a line of hoppers above the first line of hoppers facing into the solid block.

    [media]
  5. Place a chain of hoppers above the second chain of hoppers that feeds down the line of hoppers.

    [media]
  6. At the end of the chain of hoppers, place a comparator facing away from the hopper facing into a solid block, place a redstone torch on the side of this solid block and a repeater between the redstone torch and the line of redstone.

    [media]
  7. Place redstone dust on top of the solid blocks

  8. At the start of the hopper chain, place another hopper with a feeder chest on top.

    [media]
  9. Place comparators next to the containers facing away from them.

  10. Place at least a stack of items into the feeder chest.
    → ❌ Some of the comparators are not lit, indicating no item went into them

    [media]

Additional information

EDIT: This bug breaks some industrial furnace designs. The above instructions will produce a common industrial furnace design if built correctly.

It is possible that the powered/unpowered hopper is not transferring items from the chained hopper above it because the chained hopper is actually empty at the time the powered hopper becomes unpowered.

The empty container appears to be seven from the end if the repeater has the default delay of 1. If the repeater has a longer delay, different containers won't receive items. Delay 1: hopper 7; delay 2: hopper 9; delay 3: hopper 11 and hopper 3; delay 4: hopper 13 and hopper 5.

Linked issues

Attachments

Comments 11

The bug is still present in 1.14 Prerelease 2. A world save is attached.

[media]

[media]

Still in 1.14.4-pre6.

Present in 1.16 pre-2.

Still an issue in 1.16.4, breaking and replacing glitched hoppers / furnaces sometimes fixes it.

confirmed for snapshot 20w49a

1 more comments

Still an issue in snapshot 21w03a

Still an issue as of 1.17

This comment by Ilmango (https://bugs.mojang.com/browse/MC-116324?focusedCommentId=387602&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-387602) in one of the duplicates has more information about this behavior.

The comment states that a hopper transfers its first item after 7 game ticks (3.5 redstone ticks) and transfers each subsequent item after 8 game ticks (4 redstone ticks). This causes the first item to move slightly faster down the hopper line than the rest. It eventually gets far enough ahead that the second item moves faster for a while, and so on.

Ilmango's comment is all well and good, but I can't find a link or a working solution to the problem.
Ilmango assumes a large number of Furnaces, but for smaller Furnance arryas like with 8 Furnaces I have not found a solution.

I am not educated quite enough to say this for certain, but will leave it here anyways. This does look very similar to MC-6162 and it's resolved duplicate issues. If someone who knows more about redstone could look into whether or not these are the same issue that would be helpful. Otherwise, a relation link would be nice.

With that being said, I can confirm this in 1.20.6 and 24w19b:

[media]

bdm68

(Unassigned)

Confirmed

Platform

Normal

Redstone

Minecraft 1.11, Minecraft 1.11.2, Minecraft 17w06a, Minecraft 17w15a, Minecraft 1.12.2, ..., 1.16.4, 20w49a, 20w51a, 21w03a, 1.17

Retrieved