Could not pass event / org.bukkit.event.EventException: null

What the log looks like

org\.bukkit\.event\.EventException: null
Could not pass event \S+ to [^\r\n]+\r?\norg\.bukkit\.event\.EventException: null

How to fix it

1. Read the `Could not pass event <EventName> to <PluginName>` line immediately above `org.bukkit.event.EventException: null` to identify which plugin failed while listening to the event.
2. Scroll down the log until you find the `Caused by:` line, which reveals the real Java exception and the exact plugin method that broke.
3. Scan the lines above and below `Caused by:` for other plugin package names, since one plugin triggering an action (such as opening a custom inventory) can cause a second listening plugin to fail.
4. Check the failing plugin's configuration files if the `Caused by:` message mentions an invalid item, material (such as `Cannot drop AIR`), or missing world.
5. Update both the failing plugin and your Paper or Spigot build to versions that match your server's Minecraft version, or report the full log—including the entire `Caused by:` section—to that plugin's developer.

Check your own log