Items in hoppers flowing out of order

Confirmed on Windows 10 1.2.10.2.

A demo world is attached that contains a hopper loop that cycles the powered hopper contents once each time a button is pressed. Repeated presses of the button should not change the order of items in the powered hopper, but after several cycles the order does change.

We have had a discussion about this and it appears that it's working as currently intended. It's true that a hopper always pushes an item from the first non-empty slot, however this doesn't necessarily translate to preserving the order in a whole series of hoppers. Intuition would suggest that it should, but intuition is wrong in this case.

The problem occurs because all the hoppers are pushing on the same tick simultaneously, but the game can only update them one at a time, and it updates them in random order. Consider this scenario: Hopper A points to hopper B and each hopper has a single item in slot 1. When a redstone tick happens, the game can update either hopper first. If it updates hopper B first, hopper B pushes its item from slot 1 to somewhere, then hopper A pushes its item from slot 1 into hopper B, where it goes into slot 1 because it's now empty. That's the way you expected it to work.

On the other hand, if the game updates hopper A first, hopper A pushes its item from slot 1 into hopper B, where it goes into slot 2 because slot 1 is still occupied. Then hopper B pushes its item from slot 1 somewhere, which leaves it with slot 1 empty and an item in slot 2. The items are still in order, but on the next cycle things go awry. The next item from hopper A (the third item in the series) will go into slot 1, and if hopper B still has an item in slot 2 (because the game updated hopper A first), the items will now be out of order.

The underlying cause is that the game updates the hoppers in random order. This is intentional, because there is no particular ordering of the updates that solves every problem of this kind. For one thing, there's no good way to even define a general ordering of hoppers, because hoppers can be arranged in all kinds of ways, such as a loop or several feeder pipes all feeding into a common pipe. In your case, updating them from last to first would solve your problem, but that's just for the special case of hoppers arranged in straight line. It wouldn't work for a different arrangement, and the number of possible arrangements is virtually infinite.

Your problem (and similar problems) can be solved, but it requires enabling and disabling hoppers with precise timing. Unfortunately, how to do this is beyond the scope of the bug tracker. There is a community of technical minecrafters with expertise in redstone on the Minecraft Discord; they should be able to help you get it working, and might be able to point you to a tutorial if you need one.

This is a terrible design decision, and adds unnecessary randomness to a logic based system(always the best!) If you guys want redstone to actually be appreciated on this platform, you have to fix issues like this. This affects literally everything that uses hoppers, which is pretty much every contraption.

Also, java edition doesn't have issues like this! Hoppers just work, regardless of the near infinite ways to arrange them 👍

Silent I reported this over a year ago, and every time they’ve come back saying it works As intended if you build they way their diagram shows it works but for more complicated designs, ie potion machines it doesn’t. Where hoppers are placed underneath other hoppers, with timings locking and unlocking hoppers. Just doesn’t work right. My potion machine design originally made for Java. I since then modified the design to work for bedrock. And I even modified it to get around this bug. Made the foot print bigger but as long as it works I’m happy. Without the added potions since 1.9 is was 16wide x 5tall x 4 in-depth. Now it’s an extra 4 blocks now being 8 in-depth because of the added potions it’s now wider than 16 but can’t help that part.. I’ve since modified my potion machine adding several safety features. Making it taller but those safety features weren’t originally on the machine. So I’ve given up on telling mojang about bugs since they’ve come back telling me nope works great.

We're already working on achieving parity across versions where possible, and we're very keen to hear your requests or suggestions, so we'd encourage you to make a post at https://feedback.minecraft.net, or upvote an existing topic there.

If you're not sure whether your issue is a parity request or a bug, hopefully this article will help explain further: Parity Request Guide

Quick Links:
📓 Issue Guidelines – 💬 Mojang Support – 📧 Suggestions – 📖 Minecraft Wiki

I have notices this happening in Java edition 1.21 in a world that is reloaded. If a build a hopper queue in 1.21, it works fine, but when I reload the world, the order is messed up and will only be fixed if I remove and replace the hopper queue.