Your Minecraft server froze and Minecraft stopped it

Minecraft runs the world in ticks, 20 per second. If one tick takes far too long, the server's watchdog decides it has hung and stops it on purpose. Minecraft's own watchdog says A single server tick took 60.00 seconds. Paper and Purpur use their own watchdog instead, which says The server has stopped responding!. Something froze the world for a whole minute: a plugin, a mod, or a very large machine in the world. Find it, then start the server again.

What you see

• Players freeze, then lose the connection.
• The Console shows A single server tick took and a number of seconds, then (should be max 0.05). On Paper and Purpur it shows The server has stopped responding! and a thread dump, a long list that starts with Server thread dump.
• When the server has stopped after Minecraft's own message, the Why your server stopped box on Overview and above the console says The server froze, and Minecraft stopped it. and One update took the seconds, A plugin, a mod or a very large machine in the world is usually the cause; spark's profiler shows which.

Find what froze it

1. Start the server again.
2. In Files, open crash-reports and the newest file, or read the Console around the watchdog lines (on Paper and Purpur, the thread dump). They show what the server was doing when it froze. A plugin's or mod's name there is your best lead. See How to read your Minecraft server log and crash reports.
3. If the server lags before it freezes, run Profile 60 s on the Server health card on Overview while the lag is happening. It names the plugins or mods that use most of the main thread: How to check your Minecraft server health with TPS and the spark profile.
4. Update or remove what it names, or change the setting that makes it run too often.

Common causes

• A plugin or mod doing a big job in one go, such as generating or scanning a large area.
• A huge machine or farm: a long redstone clock, thousands of items on the ground, a very dense mob farm.
• Players exploring far into new land, which the server has to generate: How to pregenerate your Minecraft world does that work ahead of time.

The Watchdog limit

On Vanilla and the mod loaders, the time limit is the Watchdog limit in Settings, Server Properties (Java), 60000 milliseconds by default. Paper, Purpur and Spigot switch that watchdog off and use their own, set by timeout-time in Spigot Settings (spigot.yml), 60 seconds by default. The panel describes the Watchdog limit as Milliseconds a single tick may take before the server decides it has hung and shuts itself down. -1 turns the watchdog off, which is useful while tracking down a slow plugin.

Leave it on in normal play. With the watchdog off, a frozen server stays frozen with players stuck in it, instead of stopping. Turn it off only for a short time while you find a slow plugin, and turn it back on after.

Good to know

• A server that lags a lot is the same problem in a smaller form: How to reduce lag on your Minecraft server and Your Minecraft server says Can't keep up.
• Other causes the panel names: How to see why your Minecraft server stopped.