Allow unofficial versions

By default, your server asks Mojang’s servers to confirm the identity of every player. Anyone whose account can’t be verified is turned away.

On Mineon, two clicks

1. Open the Settings tab, Access group.
2. Switch Verify Minecraft accounts off, then save.
3. Restart the server. Changes are only read at startup.

Bedrock players aren’t affected. They come in through Floodgate, which handles their identity separately, whether verification is on or not.

By hand

The setting lives in server.properties, at the root of the server:

max-players=20
motd=A Minecraft Server
online-mode=false          <-- here
spawn-protection=16

false lets everyone in, while true turns verification back on.

Restart the server for it to take effect.

The consequences

Anyone can take any username. That’s the whole point of the setting: nothing proves any more that a player is who they claim to be.

You can deal with this by using login plugins, which make players enter a password when they join.

Skins disappear. They’re served by Mojang; plugins such as SkinsRestorer exist to work around this.