Your Minecraft server crashed. You open the log file and see 500 lines of text that looks like alien code. Java class names, file paths, thread dumps. Your eyes glaze over.
Here is the secret: you only need to read about 5 lines. The rest is background noise. Here is how to find those 5 lines.
Where to Find Logs
| File | Location | Contains |
|---|---|---|
| Latest log | logs/latest.log | Everything from the current/last session |
| Crash report | crash-reports/crash-*.txt | Detailed crash with system info |
| Old logs | logs/YYYY-MM-DD-*.log.gz | Compressed logs from previous days |
Start with latest.log. If the server generated a crash report, check crash-reports/ too.
The Three Things to Search For
Open the log file and search (Ctrl+F) for these keywords:
1. "ERROR"
Lines with [ERROR] or ERROR are actual problems. Most of the log is [INFO] which is normal operation. Filter for ERROR first.
Example:
[12:34:56 ERROR]: Could not load 'plugins/BrokenPlugin.jar'
org.bukkit.plugin.InvalidPluginException: java.lang.NoClassDefFoundError: net/milkbowl/vault/economy/Economy
This tells you: BrokenPlugin failed to load because it needs Vault and Vault is not installed.
2. "Caused by"
In a Java stack trace, the most important line is "Caused by:" at the bottom of the trace. Java prints errors in reverse order. The real cause is at the bottom, not the top.
Example:
java.lang.RuntimeException: Error loading plugin
at org.bukkit.plugin.SimplePluginManager.loadPlugin(...)
at org.bukkit.plugin.SimplePluginManager.loadPlugins(...)
Caused by: java.sql.SQLException: Access denied for user 'minecraft'@'localhost'
The actual problem: database access denied. The username or password in the plugin config is wrong.
3. "WARN" (sometimes)
Warnings are not always problems. But some warnings indicate issues that lead to crashes:
[12:34:56 WARN]: Can't keep up! Is the server overloaded? Running 5432ms behind
This means the server is lagging badly. 5432ms behind means it is about 5 seconds behind real time. Check for entity overload, chunk loading issues, or plugin problems.
Reading a Crash Report
Crash reports are generated when the server crashes hard. They look intimidating but follow a pattern:
---- Minecraft Crash Report ----
Time: 2026-02-28 12:34:56
Description: Exception in server tick loop
java.lang.OutOfMemoryError: Java heap space
at net.minecraft.world.level.chunk.LevelChunkSection.<init>(...)
at net.minecraft.world.level.chunk.LevelChunk.<init>(...)
Line 1 (Description): "Exception in server tick loop" tells you the crash happened during normal game processing.
Line 2 (Error): "OutOfMemoryError: Java heap space" is the actual error. The server ran out of RAM.
Fix: Increase RAM allocation or reduce simulation distance.
Common Errors and Their Fixes
OutOfMemoryError
java.lang.OutOfMemoryError: Java heap space
Problem: Not enough RAM allocated. Fix: Increase Xmx in startup flags. Or reduce view-distance and simulation-distance to lower memory usage.
NoClassDefFoundError
java.lang.NoClassDefFoundError: net/milkbowl/vault/economy/Economy
Problem: A plugin needs a dependency that is not installed. Fix: Install the missing plugin (Vault in this case). The class name usually tells you which plugin is needed.
PluginException: "Plugin already initialized"
org.bukkit.plugin.InvalidPluginException: Plugin already initialized!
Problem: Two copies of the same plugin are in the plugins folder. Fix: Check for duplicate .jar files. Delete the older version.
SQLException: Access denied
java.sql.SQLException: Access denied for user 'minecraft'@'localhost'
Problem: Database credentials are wrong. Fix: Check the plugin's config.yml for the correct database username, password, and database name.
SocketException: Address already in use
java.net.BindException: Address already in use: bind
Problem: Something else is already running on port 25565. Fix: Stop the other process or change the port in server.properties.
UnsupportedClassVersionError
java.lang.UnsupportedClassVersionError: ... has been compiled by a more recent version of the Java Runtime
Problem: A plugin was compiled for a newer Java version than your server runs. Fix: Update your Java version. Most modern plugins need Java 17 or 21.
How to Get Help with Logs
If you cannot figure out the error:
- Copy only the relevant lines (the ERROR section and the "Caused by" line)
- Paste them on mclo.gs (a Minecraft log sharing site). Share the link instead of pasting 500 lines of text
- Post in the plugin's Discord or support forum with the mclo.gs link and describe what you did before the crash
Do not paste your entire log file into a Discord chat. Nobody will read it. Use mclo.gs or a pastebin service.
Preventing Crashes
Most crashes are preventable:
- Keep server software and plugins updated
- Do not install plugins for a different Minecraft version
- Monitor RAM usage with
/spark healthbefore it runs out - Test plugin updates on a staging server first
- Read the console after every restart. Fix warnings before they become errors
Space-Node's control panel includes a console viewer where you can search through logs directly in your browser. Get started here.
