Players have updated past the server
What it looks like in your log
Outdated server! I'm still on 1.20.1
What causes it
A client on a newer Minecraft version tried to join, which the server cannot accept.
How to fix it
The player selects the server’s version in their launcher installation, or the server is updated to the version the players are on.
Why it happens
The client is on a newer Minecraft version than the server. The launcher updates itself, the server does not, and one day the join stops with the server announcing the version it is still on. The number is exact: 1.20.1 and 1.20.4 are different protocols.
Fix it step by step
- 1Play on the server's versionIn the launcher, create an installation on the version the message names. Installations sit side by side; nothing is lost.
- 2Or update the serverIf the players have moved on, move the server. Back up the world first, because worlds do not downgrade. Plugins and mods must have builds for the new version.
- 3On a modpack, the pack decidesUpdate the pack to a release on the newer game version rather than swapping the server jar. Mods pinned to the old version will not load on the new one.
- 4Bridge it with ViaVersion if neededViaVersion on the server lets newer clients join an older server while you decide. Some features will not work across the gap.
If that didn't work
If the client is on the same version and still gets this, a proxy in front of the server is on a different version to the backend. Match all three.
Not sure this is your problem? Paste your log and Roastd will tell you which of these it actually matched, and what else it found.
Check your own log