Common errors in the console

This page explains the error lines owners see most often in the console, in plain words, with the fix for each. If you are signed in, the help bot can find these for you: ask it what is wrong with your server.

Can't keep up! Is the server overloaded?

The server runs 20 ticks a second. This line means it fell behind, so players feel lag: blocks take a moment to break, mobs jump about.

Common causes: many mobs, items or big farms, a high view distance, heavy plugins, or players exploring new land fast (new chunks are generated as they go).

Fixes:

1. Check TPS and memory in Analytics.
2. Lower the view distance and simulation distance in Settings.
3. Limit mob farms and clear dropped items.
4. Remove or replace heavy plugins.
5. On a paid plan, pre-generate the world. See Worlds.

One line after a restart or a big explosion is normal. Many lines every minute is a problem.

java.lang.OutOfMemoryError

The server ran out of memory. It may freeze or crash, and it restarts by itself.

Fixes:

1. Lower the view distance and simulation distance.
2. Remove heavy plugins and clear big farms or item piles.
3. If it keeps happening, move to a plan with more memory. See Credits and plans.

Raising the memory in the Java flags above what your plan gives does not help: the plan's limit still applies.

UnknownDependencyException or "missing dependency"

A plugin needs another plugin to be installed first, for example Vault or ProtocolLib, and it is not there. The line names the missing plugin.

Fix: install the missing plugin from the Plugins page, then restart.

NoSuchMethodError, NoClassDefFoundError or "Unsupported API version"

A plugin was made for a different Minecraft or Paper version, so it calls code that is not there.

Fix: update the plugin to the release made for your Minecraft version. If there is none yet, remove it, or switch your server to a version the plugin supports in Versions and software (a backup is made first).

UnsupportedClassVersionError

A plugin was built for a newer Java than your server runs. Servers here run Java 25, so this usually means a broken or very new build of the plugin. You cannot change the Java version yourself.

Fix: install the release of the plugin that matches your Minecraft version, or remove it.

InvalidConfigurationException or "while parsing a block mapping"

A config file (a .yml file) has a mistake, usually after an edit by hand: a tab instead of spaces, a missing space after a colon, or a quote that is not closed. The line says which file and which line.

Fix: open the file in Files, fix that line, and restart. Or restore just that file from a backup with Restore files or folders. See Backups and restores.

You are not white-listed on this server

The whitelist is on and the player is not on it.

Fix: add the player on the Players page, or turn the whitelist off.

Outdated client or Outdated server

The player's Minecraft version does not match the server.

Fix: turn on Versions, Older versions so players on older versions can join, back to 1.8. A player on a newer version than the server needs to wait for an update or change version. See Versions and software.

Failed to read level.dat, or chunk errors

Part of the world could not be read. This can happen after a hard stop or a bad upload.

Fix: restore a recent backup. Restore into a new server lets you check it first.

Still stuck

Run a diagnosis (see Troubleshooting), or ask in our community Discord (link TBD).