How to Change Minecraft Server Version (1.8–1.21) Without Losing Your World

This guide shows you how to safely change your Minecraft server version without deleting your existing world, using the Multiverse-Core plugin.
It allows you to run multiple worlds in parallel on different game versions and test upgrades without data loss.

1. Requirements

Before you start, make sure you have:

A Spigot or Paper server (Vanilla is NOT supported)
The Multiverse-Core plugin (Required)

Download:

https://www.spigotmc.org/resources/multiverse-core.390/

Installation:

Download the .jar file.
Upload it to:

plugins/

Restart your server.

Make sure Multiverse-Core loads correctly in the console after restart.

2. Creating a Second (or Additional) World

After the plugin loads, you can safely create brand-new worlds without touching your main map.

Generate a normal world

/mv create WorldName normal

Generate a flat world

/mv create WorldName normal -t FLAT

Generate a Nether world

/mv create WorldName nether

Generate an End world

/mv create WorldName end

The world will be generated automatically and added to the server.

3. Switching Between Worlds

Teleport to another world:

/mv tp WorldName

(Replace WorldName with your world name.)

List all worlds on the server:

/mv list

This lets you keep:

Your old production world
A new test world for a newer version
Both running at the same time

4. Setting Game Modes for a Specific World (Optional)

You can force a specific gamemode when players enter a world.

Example – Set Creative mode for a world:

/mvg set gamemode creative WorldName

Each world can have its own rules and settings.

5. Deleting a World (If Needed)

/mv delete WorldName

Optionally, you may also manually delete the world folder from:

/worlds/

or from the main server directory.

⚠️ Warning: This action is permanent and cannot be undone.

6. Important Notes

Each world is stored in a separate folder.
All worlds run in parallel and never overwrite each other.
Multiverse fully manages:
- World generation
- Teleportation
- Per-world settings

How to Upgrade from Minecraft 1.8 to 1.21 Without Losing Your World

The safest migration process:

Create a full server backup
Upgrade your server software to a newer version (e.g. Paper 1.21)
Keep your old world unchanged
Create a new world for the new version:

/mv create new_world normal

Let players freely switch between old and new worlds

This is the most secure way to test or migrate between Minecraft versions without any data loss.