====== .dupe ======

<WRAP 516px>
^  .dupe  ^^
|{{ cmd:dupe:dupe.webp?500x235 |The .help entry for .dupe.}}||
^Type|[[:Command]]|
^Category|[[:No Category|none]]|
^In-game description|"Duplicates items using a book & quill."|
^[[:keybinds#default_keybinds|Default keybind]]|none|
^Source code|[[https://github.com/Wurst-Imperium/Wurst7/blob/1.17/src/main/java/net/wurstclient/commands/DupeCmd.java|net/wurstclient/commands/DupeCmd.java]]|
^Supported Minecraft versions|1.16.3 - 1.17|
</WRAP>

.dupe is a [[:command|chat command]] that allows the user to duplicate items in survival mode. It does this by corrupting the NBT data of a [[mc>book and quill]] item so that the server fails to save the player's inventory.

The glitch behind ''.dupe'' was originally discovered by [[gh>Gaider10]] and published on January 22, 2021((https://github.com/Gaider10/BookDupe)).

===== Usage =====

Before using this command, the player must acquire a [[mc>book and quill]] and a [[mc>chest]] (or some other container).

  - Equip the book and quill item in the main hand slot.
  - Store the items to duplicate somewhere in the player's inventory.
  - Disconnect from the server and reconnect. This causes the server to save the player's inventory.
  - Take the items to duplicate out of the player's inventory (e.g. by storing them in a chest).
  - Run the ''.dupe'' command. The player should be immediately kicked from the server, but this time the inventory is not saved.
  - After reconnecting to the server, the items will still be in the player's inventory, but the same items are now also in the chest.

This process can be repeated over and over again. The book and quill can just be left in the main hand slot, but the disconnecting and reconnecting step has to be done every time.

===== Compatibility =====

<WRAP center round important>
Minecraft 1.17.1 has patched the .dupe command. It will keep working in older Minecraft versions.
</WRAP>

[{{cmd:dupe:spigot_server.webp?400|Pressing F3 shows the type of server in the top-left corner.}}]

This item duplication glitch is known to work on vanilla Minecraft 1.16.3 - 1.17 servers. Bukkit-based servers seem to have patched this glitch.

^  Minecraft version  ^  Vanilla  ^  Fabric  ^  Bukkit  ^  Spigot  ^  Paper  ^
^1.17.1 and later|  ✘  |  ✘  |  ✘  |  ✘  |  ✘  |
^1.17.1-pre1|  ✘  |  ✘  |  ✘  |  ✘  |  ✘  |
^1.17|  ✔  |  ✔  |  ✘((Tested with Bukkit version 3162-Bukkit-b121d3b.))  |  ✘((Tested with Spigot version 3162-Spigot-f773da8-b121d3b.))  |  ✘((Tested with Paper build #64.))  |
^1.16.5|  ✔  |  ✔  |  ✘((Tested with Bukkit version 2991-Bukkit-f3f3094.))  |  ✘((Tested with Spigot version 2991-Spigot-018b9a0-f3f3094.))  |  ✘((Tested with Paper build #567.))  |
^1.16.4|  ✔  |  ✔  |  ✘((Tested with Bukkit version git-Bukkit-3eb7236.))  |  ✘((Tested with Spigot version git-Spigot-37d799b-3eb7236.))  |  ✘((Tested with Paper build #416.))  |
^1.16.3|  ✔  |  ✔  |  not tested  |  not tested  |  not tested  |

When this glitch doesn't work on a server, the player will not be kicked and will instead receive a book titled "If you can see this, it didn't work". When it doesn't work on Paper servers, the player is kicked with the message "[[:Book too large!]]". When it doesn't work in Minecraft [[mc>1.17.1-pre1]] and later versions, the player gets kicked as usual, but the items don't get duplicated.

===== Videos =====

{{youtube>y0dv3faUU4A}}

{{youtube>sdLmTo97kDk}}

===== See Also =====

  * [[:Book Too Large|The "Book Too Large" error]]
  * [[:dupe unknown command|The "Unknown command: .dupe" error]]

===== Changes =====

^Version^Changes^
|[[update:Wurst 7.14]]|Added ''.dupe''.|
|[[update:Wurst 7.16]]|Removed ''.dupe'' in Minecraft 1.17.1 and later versions.|

{{tag>item_duplication NBT_data}}