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Outdated Client / Server

A player is rejected with 'Outdated client!' or 'Outdated server!'. The two are simply on different Minecraft versions, and their network protocols are incompatible, so they cannot connect.

What does this error mean?
Each Minecraft version speaks a specific protocol. 'Outdated client' means the player's version is older than the server's, 'Outdated server' means it is newer. Either way, the versions must align (or be bridged) to connect. 
Outdated client! Please use X / Outdated server! I'm still on X
Most Common Causes
  • The player is on a different Minecraft version than the server.
  • The server was upgraded but players have not updated.
  • A player using a snapshot or an older release.
  • A modpack pinned to a version that differs from the server.
  • No version-bridging plugin installed.
How To Diagnose
  1. Read the message, it names the version the other side expects.
  2. Confirm the exact server version with '/version' (or the panel).
  3. Have the player check their selected version in the launcher.
  4. Decide whether you want to bridge versions or enforce one.
Recommended Fixes
  • Match the version
    Have players select the exact Minecraft version the server runs.
  • Add ViaVersion
    Install ViaVersion (and ViaBackwards) on the server to let newer/older clients connect.
  • Announce the version
    Tell players the required version so they switch in the launcher.
  • Plan upgrades together
    Coordinate server and player updates so they stay in sync.
Analyze My Log
Frequently Asked Questions

Only with a bridging plugin like ViaVersion. Otherwise the versions must match exactly.

It translates between protocol versions so clients on other versions can connect to your server.

In the launcher, create/select an installation set to the server's version.