ProtocolLib

What it does

ProtocolLib lets plugins read and change the packets the server sends to players: fake blocks, disguises, custom tab lists, anti-cheat checks. On its own it does nothing visible. You install it because another plugin lists it as a dependency.

Install

Put the jar in plugins and restart. The important part is the version.

Getting the right version

ProtocolLib hooks deep into Minecraft, so every Minecraft update can break it. Rules of thumb:

• For a version that's been out a while, the latest release on SpigotMC or GitHub is fine.
• For a brand new Minecraft version, the release often isn't ready. ProtocolLib's development builds (linked from its GitHub page) usually support it first.

If you update Minecraft, update ProtocolLib at the same time.

Common problems

A long error at startup mentioning ProtocolLib and your Minecraft version, or "This version of ProtocolLib does not support": your ProtocolLib is too old for your Minecraft version. Install the newest build (a development build for a new Minecraft version).

Plugins say ProtocolLib is missing: check the jar is directly in plugins and the console shows it enabling. If ProtocolLib failed to start, every plugin that needs it fails too, so fix ProtocolLib first.

Errors blaming another plugin, with ProtocolLib in the stack trace: usually that plugin is out of date, not ProtocolLib. Update the plugin named.

Performance

ProtocolLib itself adds very little. Plugins that use it to inspect every packet (some anti-cheats) cost more.