Troubleshooting & Performance

Players who can't break or place blocks near spawn are usually inside spawn protection. Set spawn-protection to 0, or check claim plugins, permissions and game mode.

Most connection errors come from a wrong address or port, a server that is offline or still starting, or Bedrock players using the wrong port. Check these first.

Restoring a backup is the safest fix for a corrupted world. If you have none, level.dat_old and region editors like MCA Selector can save most of it.

The server crashed while updating the world. The crash report names the cause, often one broken entity or block entity at specific coordinates. Remove it carefully, with a backup first.

This error means the server, or a plugin, tried to use a port it doesn't own. Never change server-port yourself; the panel assigns it. Give plugins their own extra port from the Network tab.

These errors mean Minecraft's login check failed. Usually the player's launcher session expired, they use a non-premium launcher, or a proxy network is set up wrong.

spark records what your server spends its time on and gives you a link to a report. Use /spark tps, /spark health and /spark profiler to find the plugin, mod or entity behind your lag.

First work out which lag you have: low TPS (server), high ping (network) or low FPS (your PC). Then measure with spark and fix the real cause instead of hiding it.

Your server writes everything to logs/latest.log and saves crashes in the crash-reports folder. Here is where to find them and how to spot the line that matters.

A server that stops right after Start prints the reason in the Console. Usually it's a broken plugin or mod, the EULA, wrong Java after a manual change, or a full disk.

These errors mean the player's mods don't match the server's. Install the exact same modpack, mod versions and loader version on both sides.

A few safe changes to view distance, simulation distance, entity and item settings make a big difference. Change one thing at a time and measure with spark.

java.lang.OutOfMemoryError means the server needed more memory than it has. Find what is using it (too many chunks, entities, plugins or a big modpack) before you upgrade.

The player's game version and the server's version don't match. Join with the same version as the server, change the server version in the Versions tab, or add ViaVersion.

Generating new land is one of the heaviest jobs a server does. Use Chunky to generate the world ahead of time, then add a world border so players never trigger it during play.