critical

A plugin was built for a newer server version

Q: What does "org.bukkit.plugin.InvalidPluginException: Unsupported API version 1.21" mean?

A plugin was built for a newer server version. A plugin declares an API version newer than this server supports. Update the server to the version the plugin targets, or install the plugin build made for the version you run.

Applies to Paper, Vanilla.

What it looks like in your log

org.bukkit.plugin.InvalidPluginException: Unsupported API version 1.21

What causes it

A plugin declares an API version newer than this server supports.

How to fix it

Update the server to the version the plugin targets, or install the plugin build made for the version you run.

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

Errors that travel with this one

A plugin is missing another plugin it depends onorg.bukkit.plugin.UnknownDependencyException: Unknown/missing dependency plugins: [Vault]
A plugin failed to loadCould not load 'plugins/MyPlugin.jar' in folder 'plugins'
A plugin needs a newer Java than the server runsCould not load 'plugins/MyPlugin.jar' in folder 'plugins': java.lang.UnsupportedClassVersionError: class file version 65.0
A file in the plugins folder is not a pluginorg.bukkit.plugin.InvalidDescriptionException: Invalid plugin.yml
Two copies of the same plugin are installedAmbiguous plugin name `Essentials' for files `plugins/Essentials.jar' and `plugins/EssentialsX.jar'
Wrong file for this server typeorg.bukkit.plugin.InvalidDescriptionException: Jar does not contain plugin.yml