How to Dupe Items in Minecraft Java 1.21.10

What You Need

• 1 Barrel
• The items you want to duplicate (can be shulker boxes, etc.)
• Access to Task Manager (Windows) or Activity Monitor (Mac)

Step-by-Step Guide

1. Place the barrel in your world.
2. Press ESC and choose Save and Quit to Title.
3. In the world menu, click Edit → Make Backup (optional, but recommended).
4. Re-enter your world.
5. Go to Options > Video Settings and set:
   • Render Distance: Max
   • Simulation Distance: Max
   • Max Framerate: Lowest
   • Biome Blend: Max
6. Open the barrel and put in all the items you want to dupe. Don't close the barrel menu.
7. Press Ctrl+Shift+Esc (Windows) or open Activity Monitor (Mac).
8. Find OpenJDK Platform binary (or Minecraft Java process), select it, and click End Task (or Force Quit).
9. Restart Minecraft and re-enter your world. If it worked, you'll have the items in both your inventory and the barrel.
10. If your game is laggy, reset your video settings to normal.

Troubleshooting & Tips

• If the dupe fails, try again and make sure you don't close the barrel menu before ending the task.
• Always make a backup before attempting any glitch to avoid losing items.
• This glitch may be patched in future updates. Works as of October 2025.
• Works best in singleplayer. May not work on servers.

Why This Works

This dupe glitch takes advantage of how Minecraft saves world and inventory data. By crashing the game at the right moment, the game saves both the items in your inventory and in the barrel, duplicating them. This method is popular because it's simple, doesn't require mods, and works on the latest version.

Video Walkthrough

For a full demonstration, watch the video above. It shows every step, including the exact timing for ending the Minecraft process and what to do if something goes wrong.