“Can't keep up! Is the server overloaded?” in Minecraft: What It Means and How to Fix It

What the warning means

A Minecraft server does its maths 20 times a second: each round is a tick, and it has 50 milliseconds to move everything (mobs, redstone, crops, players). If a tick takes longer, the next one starts late; when the delay piles up, the server says so in the console and skips the ticks it owed to catch up.

The numbers say how far behind it fell: “Running 2500ms or 50 ticks behind” is two and a half seconds, 50 ticks the world never lived. That's why, when it shows up, blocks take ages to break, animals jump around and food doesn't run down at its normal pace: it's server lag, the same for everyone playing.

It has nothing to do with each player's connection. If only one player is struggling and the console says nothing, it's their connection or their computer (high ping on a server).

When it's normal

One or two warnings at startup, while the server loads the world and the plugins, are normal: starting costs more than playing. So is a single one when someone first walks into an area that has never been generated, or when the world is saved.

If your server runs at home, it shows up with a huge number (“Running 300000ms”) after the computer sleeps or hibernates, or if the system clock changes: the server thinks it has lost whole minutes. It isn't load; it goes away by itself.

What isn't normal is seeing it every few minutes with people playing. Then something is asking for more than the server can give, and it's worth knowing what before you change anything.

Measure how far behind it is

1. TPS

   On Paper, tps in the “Console” (or /tps in chat as an op) gives the average for the last minute, the last 5 and the last 15. 20 is perfect; below 18 you start to notice it and below 15 you notice it a lot.

2. Milliseconds per tick

   mspt (on Paper) says how long each tick really takes. Below 50 it has room to spare even if TPS is at 20; if it gets close to 50 or goes over, that's the warning. On any server since 1.20.3, tick query tells you the same (the /tick command (in Spanish)).

3. Memory and CPU

   In the panel, “Home” shows the memory, CPU and disk meters, and “Performance” the graphs for the last few hours. That way you see whether the delay matches the memory being full or the CPU being maxed out.

Find the cause with spark

spark comes with Paper and tells you where each tick goes: which plugin, which mod, which entity type or which part of the world. It's what saves you days of removing plugins blindly.

1. Start the profiler

   With people playing and the warning showing up, type spark profiler start in the “Console”.

2. Leave it for a few minutes

   Three or four minutes are enough for it to catch the bad moment. Don't restart in the meantime.

3. Stop it and open the link

   spark profiler stop gives you a link to the report. Look for what takes the biggest percentage under “Server thread”: the name of the plugin, the mod or the entity type usually shows up by itself.

The usual causes and how to fix them

1. World generation

   Exploring new areas, especially flying with elytra or by boat, forces the server to create the terrain on the spot, and that's what costs the most. The fix is to generate it beforehand, calmly: pregenerate with Chunky, plus a border so nobody goes further.

2. Too many entities

   Farms with hundreds of animals, villagers piled up or items lying on the ground. spark shows it as “entity tick”. What there is and how to bring it down without breaking farms, in entities and lag (in Spanish).

3. Redstone that never stops

   Redstone clocks that are always on, chains of hoppers or automatic farms in areas that stay loaded all the time. Switching clocks off when they aren't in use and replacing spare hoppers with something else makes a difference.

4. High view distance

   view-distance and simulation-distance in server.properties say how many chunks the server keeps loaded around each player, and they grow with the square: going from 8 to 16 is four times the work. Lowering simulation-distance (what moves) takes off more load than lowering view-distance (what you see). They're changed in the panel's “Settings” (what each option does).

5. A plugin or a mod

   If spark points at one, check whether it has a new version or whether its config can be made lighter. If it started when you added it, remove it and check. On Fabric, performance mods help (which ones (in Spanish)).

6. Memory at its limit

   With memory always full, Java stops now and then to clean it up and the tick gets longer: the warning shows up even if nothing odd is happening in the world. It happens above all with modpacks. How much RAM your server needs.

If your server is on NapNodes

New Minecraft servers are delivered on Paper and with the world already generated around the spawn point, so the first walks around don't load it. If it still shows up often, do the above: spark comes installed and the distance settings are in “Settings”, and they apply on restart.

Every plan has a CPU cap (the CPU column in the plans table) and the RAM you pay for is yours alone: nobody else uses it. If spark doesn't point at anything odd and in “Performance” the CPU sits at its cap or the memory is full all the time, the server has fallen short for what you're doing: more RAM is added without reinstalling anything, and the bigger plans also come with more CPU.

Before that, it's worth optimising Paper: a few settings in its files take off a lot of load without anyone noticing while they play.

To see the whole log at a glance

If the console is full of messages and you don't know which ones matter, paste the log into the Minecraft log analyzer: it counts how many times “Can't keep up” shows up, points out the real errors and tells you which guide to read. It runs in your browser: the log isn't uploaded anywhere.

Frequently asked questions