Can't keep up! Is the server overloaded? means the server fell behind. Minecraft runs the world at 20 ticks per second, and when it cannot finish its work in time it skips ahead to catch up, and writes this line with how far behind it was. Once in a while is harmless. If it repeats while players are on, the server lags: measure it on the Server health card and find the cause.
Read the message
The full line looks like this:
Can't keep up! Is the server overloaded? Running 2500ms or 50 ticks behindThe two numbers say the same thing: 2500 milliseconds is 50 ticks of 50 milliseconds each. The bigger they are, the longer the server was stuck.
Current Paper builds no longer print this line: they catch up on missed ticks without a message. On Paper and Purpur, watch the Server health card instead.
When you can ignore it
- Once or twice while the server starts, or right after a big job such as generating new land or loading a large area.
If players do not notice anything and the line does not come back, there is nothing to fix.
When it matters
The line repeats every few minutes, and players see blocks come back after they break them, mobs jump around, or a delay on every action. Then:
- Open Overview and look at the Server health card while players are on. It shows the ticks per second (TPS) and the Tick time, and a verdict such as Some lag or Heavy lag.
- Click Profile 60 s under What slows it down while the lag is happening. The result names the plugins or mods that took the most time. See How to check your Minecraft server health with TPS and the spark profile.
- Fix what it names, then check again: How to reduce lag on your Minecraft server.
Common causes
- Players exploring new land, which the server has to generate. Pregenerating the area around spawn does that work once, ahead of time: How to pregenerate your Minecraft world.
- A high view distance or simulation distance for the number of players.
- Large farms, many mobs in one place, hoppers and redstone clocks.
- A plugin or mod that runs a heavy task.
If it ends in a crash
If the server freezes so long that it stops with A single server tick took 60.00 seconds, see Your Minecraft server froze and Minecraft stopped it.
