Tools with unbreaking enchantment break, disappear from slot then reappear

I host a server and play almost exclusively SMP as a result, and it seems like this is a bug related to the Unbreaking enchantment. From what I can tell, the client and server are having a disconnect somewhere, causing the client to say that the item "Broke" and remove it from your inventory temporarily, until the server corrects it and gives you the item back.

Affects 1.4.7 too. Also the durability meter changes without using the tool.

I've only ever had this happen when using an unbreaking-enchanted pickaxe in multiplayer. So I assume (as others have said) that it's related to these two things.

I agree about the unbreaking enchantment but I'm playing SSP so I confirm it in SSP 1.4.7 too.

This happens for me in singleplayer and multiplayer when using any tool that has an Unbreaking enchantment on it.

This happened to me just now in 1.4.7 with an Unbreaking III pickaxe.

To see if it is actually breaking, someone might want to press F3 + H to get the durability shown.

Will, I tried doing that, and I'm finding that 'actually breaking' is a hard thing to predict with an Unbreaking tool. On an unenchanted tool, you could accurately say that a durability of 0 means that the next use will break the tool. But an Unbreaking tool can remain at 0 for several uses. To directly answer your suggestion, the glitchy breaks as well as the real breaks all occur when durability is 0. Maybe though, I misunderstand what you might mean by 'actually breaking'?

If the durability drops to 0 don't use it again because it is unpredictable whether it is going to break, not just because of the bug but because of the unbreaking enchantment. As I mentioned before, because of the bug the durability meter is not reliable. In order to make it refresh and show the real value what I do is pick up the tool and place again in the inventory. The durability meter will then refresh and show the actual value. I'm sure this behavior is connected with the breaking and reappearance of the tool and both are connected with this bug on unbreaking enchantment.

What you say makes sense, Marios. It sounds like a case of client-server sync issues.

I just had this happen to me on 13w05b on an Unbreaking I Iron Shovel, so it has yet to be fixed.

If i use something to freecam in server and then break blocks, client will show that pickaxe is used!

This seems to happen with unbreaking tools when the tool would otherwise break (i.e.: it has a single unit of durability remaining), but the unbreaking subsequently re-adds the use to the tool. The client doesn't know that the server might un-break the tool, so it subtracts one durability, makes the tool break, then the server responds, "Oh no, it's fine don't worry about it, it's still got a use left."

It has to do with the formula they use to determine how much the tools durability goes up due to the enchantment level.. it can result that when the tool breaks the enchanment deletes first by mistake and then you get a negative durability... because negative durability cant exist is change the negative number into a positive (i.e. -15 becomes 15) making it restore in your inventory.

Just had this problem in SMP (1.6.2), would anyone be so kind and update the "affects versions" ?

@Th3F4114n0n3 I've had this regularly happening with plain stone swords, so I conclude the enchantment is not the (only) cause.

This is often in muliplayer when it lags:
You break a block, but the server doesn't answer but your client version already subtract one health point of your tool. When the lag is away the client and the server synchronise and you get the tool back

I suppose it is like this

Not only servers, but what I'm experiencing is maybe another bug.
What I can confirm is that at the end of a life of a tool with Unbreaking on it, the pickaxe sometimes behaves very strange (especially with higher levels of Unbreaking).

I should think it would be easiest to take away the job of determining when a tool is broken from the client. Only the server/internal server should track the tool's status. (Not really sure why the client does it anyway, after release 1.3)
(There are probably two bugs present here, my proposal should fix at least one of them.)

This used to happen to me on servers way back in beta 1.2, but I did have it happen somewhat recently with enchanted tools.

I'm playing on a 1.7.4 server, and this is still the case. Mostly when I have an unbreaking pickaxe. I click on the slot with another tool and it's back for 2-3 uses.

So, to summarize it:
It can be caused by server lag and/or the Unbreaking enchantment.
I can confirm the part with the Unbreaking enchantment, not the one with the server lag though.

Honestly, I think server lag might be involved. Maybe the game thinks you still have some uses left while the server says no? Or am I understanding MC's logic wrong?

If it was just a server lag problem I would have thought it would not exist in Single Player as well?

Darren Hills: It should only have a problem in Singleplayer with Pickaxes with Unbreaking on them. Do you also experince this issue without Unbreaking being on the Pickaxe?

It's been a while since I experienced this but from what I remember it was always with the Unbreaking enchantment on. To me that suggests a calculation of amount of durability left before calculation of unbreaking effect.

I.e. Pickaxe has 1 durability left.
I use that 1 durability and pick breaks
Unbreaking effect is then calculated, and says nope it didn't break.

Not saying thats a conclusive answer or anything lol

Still affects 14w07a

This is indeed because of Unbreaking. Tested multiple times. Only Unbreaking tools come back from the dead. It seems that tools that have one use left break before the game calculates if the use counts or is absorbed by the Unbreaking enchantment.

This remains an issue in the newest snapshot.

Simple solution is to only damage tools on the serverside. This unfortunately gives the aesthetic glitch of not having the tool break apart animation.

I'll mention 1.7.9 just because it's not listed yet in the Versions Affected.

I think part of the same issue: placing a new, undamaged tool, in the same hotbar slot as a recently-broken tool, can sometimes cause the new tool to disappear

Perhaps a solution is to have unbreaking enchant not work for the last use or last few uses.

That is when a pick only has one use left, it always breaks, regardless of unbreaking enchant. That way randomness caused by server-client sync does not play a part.

As this may happen quickly perhaps the last 5 or 10 uses of a tool does not allow unbreaking, so as to ensure client-servers are in sync in a tools last moments of life.

Confirm in 14w34d, pickaxe and axe re-appear after broken. Not sure if it has anything to do with the Unbreaking enchantment though.

This happened to me in Minecraft 1.8 in single player survival. I had an iron pickaxe with Efficiency IV and Unbreaking III. When it ran out on the last block I was mining, the pickaxe made the breaking sound and disappeared like normal. I opened my inventory and moved a diamond pickaxe into the slot the enchanted iron pickaxe used to be in. When I did, the enchanted iron pickaxe suddenly reappeared and was thrown to the ground. I exited my inventory and picked it up off the ground. I was able to use it a few more times before it made the breaking sound again, broke for good and disappeared permanently. See attachments. Image "MC-1040_1.png" shows the enchanted iron pickaxe suddenly being thrown to the ground after the actions described above. Image "MC-1040_2.png" shows it back in my hotbar after I picked it back up off the ground.

I actually kind of like this "undocumented feature" as I can safely use my more enchanted tools without worry of actually killing them. It took a lot of experience and two anvils to make my diamond pickaxe get efficiency IV unbreaking III. 😃

No this isn't an "undocumented feature"
The bug is that the item is breaking visually when it's not supposed to.
The client should always reflect the server accurately so this is a bug.

Also F3+H(PC) works way more effectively at preventing you from going through a pick/tool you don't want to lose rather than hoping on a random bug to occur.

Confirmed in 1.8.7 with a player connected by LAN to my game, his enchanted picks break and then reappear when he tries to replace it in hotbar. (The "replacement" falls on the ground and the "broken" pick reappears in hotbar.) He can do this several times before it truly breaks.

Affects 15w33b, and perhaps the summary and/or description should be updated to include at least some mention of the Unbreaking enchantment?

Confirmed for 15w47c!
Just happend yesterday to me on a diamond shovel.

Confirmed for 1.8.8 and 15w51b. Here's a video demonstrating it.

Confirmed for 16w02a.

Confirmed for 16w03a.

I am running 1.8.9 Vanilla. I was playing on single-player survival. I have a stone axe with Efficiency IV, Fortune III and Unbreaking III. I used it a few times and saw the durability bar appear. A short while later I noticed the durability bar had disappeared indicating the axe had full durability again. You probably would not notice small changes in durability while the bar is in the middle of its range. But it is obvious when a tool is resurrected or when the bar disappears. Based on these reports, the game seems to randomly update durability for Unbreaking tools. I don't think this is a special case just for destroyed tools. I know that there are background checks that randomly update blocks. What routine can destroy a tool? And are there any background routines that affect tools? In my experience, there is always a random delay before the durability is increased.

Confirmed for 1.9-pre1

Please link to this comment in the description of the report.

The following is based on decompiled version of Minecraft 1.8 using MCP. All method and class names are the names used in the decompiled version.

The reason why this happens it that the method public boolean attemptDamageItem(int amount, Random rand) of the net.minecraft.item.ItemStack class runs for the client and the server. This method tries to damage an item and returns true if the item broke. The problem is that Unbreaking is random, the higher the enchantment, the higher the chance that the item does not break. As it is random it is very likely that the client and the server get different results, for example the client thinks the item broke already whereas for the server the item is still there (this is described in this report).
This method should be only called from the server which needs to send then the according package and send that the client should display the breaking particles.

Please add this example command to the description:

/give @p diamond_pickaxe 1 1561 {ench:[{id:34s,lvl:2s}]}

Confirmed for 1.9.1-pre3.

Confirmed for 1.9.3-pre3.

Confirmed for 1.9.4.

Confirmed for 16w20a.

Confirmed for 16w21a.

Confirmed for 16w21b.

Confirmed for 1.10-pre1.

Confirmed for 1.10-pre2.

Confirmed for 1.10.

Confirmed for 1.10.1.

Confirmed for 1.10.2.

I've had this happen on a notoriously laggy server (not in 1.10 nor was the server vanilla) while strip mining with unenchanted stone picks. I would mine some blocks, they would disappear without dropping items and my pick would break. I wait a few seconds (as it was normal on that server) and some of the blocks would return and I got my tool back. It is also normal on that server to fall twice from the same point 😛