You can change your server's software after setup, and it is safer than you'd expect: nothing is deleted, things only move. Here are the steps, what happens behind the scenes, and where to look if something goes wrong.

Where is it done?

The Software section in the side menu switches between nine options: Vanilla, Paper, Purpur, Spigot, CraftBukkit, Fabric, Quilt, Forge and NeoForge. You pick the Minecraft version there too; one entry carries a "Recommended" badge.

Choose, press Install / Change, and a confirmation screen appears. A running server restarts briefly and players drop while it does. Back-to-back attempts have one limit: at most 8 changes in 15 minutes, then a "too often" warning — nothing happens to your server.

What happens behind the scenes?

When the software type changes, your whole current setup moves into a profile: your worlds, your plugins and mods folders, config, resource packs, and your player lists (ops.json, whitelist.json, ban lists). The new software is installed on clean ground, not on top of them.

The rule holds even inside one family: Paper to Purpur is also a type change. What stays put: server.properties (difficulty, MOTD, system settings) and the backups in your Backups section.

Return to a software you used before and its profile is restored automatically: your world and content come back as you left them. Trying a software is never a one-way decision.

Within a family vs. across families

The plugin family is Paper, Purpur, Spigot and CraftBukkit. These four share the same plugin layout, so your plugins keep working on the new software: open Files, go into the old folder under profiles/ and move the contents of plugins across.

The mod family is Fabric, Quilt, Forge and NeoForge, and its content is incompatible with the plugin family: plugins will not run on a mod server, mods will not run on a plugin server. Vanilla belongs to neither and takes neither. That is why profiles are kept apart.

When downgrading a version

Moving to an older Minecraft version on the same software makes the panel stop you and ask for a second confirmation. The reason: a world and config files produced by a newer version will not open on an older one, and the server dies on every start.

Confirm and nothing is deleted, only renamed: your active world lands in the Worlds list as something like world_v1-21-1, version-bound settings are set aside as config_v1.21.1, and on the mod side the mods folder goes the same way. Downgrade twice to the same version and the earlier copy survives. A manual backup first is still the right move.

Things to watch

  • Mod loaders are selectable from the Pro (8 GB) package upward. On smaller packages those cards show as "Locked"; plugins still work.
  • Bedrock cross-play only works on the plugin family, with version 1.20.5 or newer and at least 4 GB. Move to the mod side and the bridge switches off automatically, locking phone players out.
  • With the bridge on, a move to a very new version can be blocked; the panel says how far the bridge has caught up. To go ahead, turn cross-play off in Settings first.
  • Servers inside a network (proxy) only run on the plugin family; mod cards are locked there too.

If something goes wrong, check in this order

  1. My world came up empty. It was not deleted. Switch back to the old software (the profile returns on its own), or open profiles/ in Files: it sits in the folder named after the old software.
  2. My plugins or mods are gone. Same place. Use the Move button in Files to bring the jars into the new plugins or mods folder — but if the family changed, moving will not help; install the equivalents again.
  3. My operator rights and whitelist are gone. Player lists move into the profile as well, and come back the same way.
  4. The server will not start and the status shows an error. Use the repair banner on the Overview page. Stop the server first; repair deletes no files; it sets the problematic config files aside.
  5. Read the console. Lines starting with [arcade] name exactly what moved where: the profile save and every file set aside.

Common mistakes

  • Re-activating the set-aside old world from Worlds after a downgrade: it was produced by the newer version, so the server dies again. Raise the version back first.
  • Assuming backups survive the server: deleting a server deletes its backups too.
  • Installing a modpack on plugin-family software; a modpack needs a mod loader.
  • Switching to the mod family while players join from phones — the bridge closes and they are locked out.

Which one should you pick?

  • A server built around plugins: Paper. Want more tuning knobs, Purpur; if you have an old plugin that only runs on Spigot, Spigot or CraftBukkit.
  • Mods or a modpack: whatever the modpack asks for — Fabric/Quilt or Forge/NeoForge. The Pro package is required.
  • Plain gameplay with nothing installed: Vanilla.
  • Phone players joining too: plugin family + 1.20.5 or newer + 4 GB.
  • Undecided: take a backup and try it — profiles let you return to your old software later.

See the software selection guide for the differences, the file manager guide for moving files, the backup guide before you change anything, and the cross-play guide for phone players.