Player lagged out (timeout due to bad connection), as a result the server didn't kick the player out of the game. Player rejoined and ended up spawning inside the old player position which then turned into a ghost. The real player can move around normally, but the ghost simply stands in place, but is able to take damage as if it were a normal player. The damage doesn't affect the player the ghost came from. After about a minute the ghost will vanish and the server will say the player left the game, but /list shows the real player and other players like normal.
DUPLICATION:
In our occurrence, we were getting the "Diamonds to You!" achievement, one player threw the diamonds to me (8 of them), on my screen I threw them back. Then I lagged out, rejoined, and I still had the 8 diamonds, however the player I returned them to retrieved them as well, and had tried to send 1 back to me again (since I threw all out at once rather than simply using the Drop Item key), which may have been collected by the ghost player. So we ended up with 15 diamonds through the lag, and these diamonds were able to be moved around and crafted with without any disappearing (as if it were a client error).
Linked issues
is duplicated by 57
MC-37543
Invisibility and invincibility glitch in multiplayer
Resolved
MC-38339
Item Duplication
Resolved
MC-39100
Inventory duplication death exploit
Resolved
MC-39149
Disconnect via Internet outage bug
Resolved
MC-39846
Duplication of all inventory items **WORKS ON MULTI-PLAYER VANILLA**
Resolved
relates to 4
Attachments
Comments 50
To duplicate:
1) Player disconnects their internet, and leaves the game their side.
2) Player connects their internet again and logs on asap.
3) Ghost will be made if the player is fast enough to log on before the server times the ghost out.
4) Kill the ghost, it will drop the items you had when you left.
I made a video showing how easy it is to exploit this bug, I was a bit afraid of sharing it because of the nature of the issue, but since Odd Man basically described how to reproduce it, here it is: http://youtu.be/glwceU6CY2Q
As you can see, in my case I don't even have to lose connection to make it happen. A couple of minutes online seem to be enough to trigger it and a normal reconnection does the trick, so to speak.
I never noticed this problem during the first days after the update. It became noticeable only about a week later, and now it happens 99.9% of the times I click on disconnect.Also, I seem to be the only player affected by it on server I play on, which makes me think the problem is related to some network configurations.
Edit: Other than item duplication, this bug can cause the opposite effect because anything contained in the ghost player's inventory gets lost when the server kicks him out.
Still an issue in 1.8.7.
Whenever I disconnect from a server my character stays logged in for the next 20 seconds, until he's timed out by the server.
I haven't really tested this in the latest 1.9 snapshots but I can confirm this is happening in 1.8.8. Me personally cannot reproduce this bug but my friend is able to do so on command. He just disconnects and log in again and everytime it works.
When this is happening he's able to kill his own ghost entity/player and thereby duplicate the items, truly game-breaking in my opinion.
Was this fixed by the fix of MC-92476?
Or is for example the method described by @unknown still working?
I can confirm this.
It happens very often when I reconnect, I'm even able to kill my clone and pick up his items.
This can be easily exploited to duplicate anything present in the affected player's inventory, especially once you figure out how a very reliable way to reproduce it.