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Reading Crash Reports and Server Logs

Reading Crash Reports and Server Logs

When a Minecraft server fails to start or unexpectedly shuts down, diagnosing the exact cause requires inspecting logs/latest.log and the crash-reports/ folder.

1. Where to Find Crash Files

  • Live Console: Navigate to the Console tab on the Dashboard to inspect real-time boot messages and stack traces.
  • Server Log: Located in logs/latest.log via the File Manager. This file contains a complete chronological record of everything that occurred during the most recent server session.
  • Crash Reports: Located in crash-reports/crash-YYYY-MM-DD_HH.MM.SS-server.txt. A crash report is automatically generated whenever an unhandled Java exception forces the server process to terminate.

2. Common Errors and Solutions

Error 1: java.lang.OutOfMemoryError: Java heap space

  • Root Cause: The server exceeded its 4GB memory allocation. This typically occurs when running heavy modpacks with excessive chunk loaders, pre-generating massive world areas, or running memory-leaking legacy plugins.
  • Solution: Reduce your simulation distance to 4, remove redundant plugins, optimize chunk loading, and install Spark to profile memory consumption.

Error 2: java.lang.UnsupportedClassVersionError

  • Root Cause: A plugin or server .jar was compiled with a newer version of Java than the one currently executing on the node. For example, Minecraft 1.20.6 and 1.21 require Java 21; running on Java 17 will trigger this error.
  • Solution: Ensure your server software selection in the Version Changer matches the appropriate Java runtime environment.

Error 3: NoClassDefFoundError or ClassNotFoundException

  • Root Cause: A plugin is missing a mandatory dependency library or API (for example, attempting to run EssentialsX Spawn without the main EssentialsX plugin, or running Vault-dependent economy plugins without Vault).
  • Solution: Check the plugin description page on Spigot or Modrinth and install all required companion plugins into /plugins/.

Error 4: net.minecraft.server.Main: Failed to start server / EULA agreement

  • Root Cause: The Mojang End User License Agreement has not been formally accepted.
  • Solution: Open eula.txt in the File Manager and change eula=false to eula=true, then restart.

3. Best Practices for Sharing Logs

When asking for assistance in the FreeMcHosting Community Discord, follow these safety practices:

  • Do Not Share Raw Passwords: Never share your database passwords, RCON secret keys, or webhook URLs.
  • Use Pastebin Tools: Use public paste tools (like pastebin.com or mclo.gs) to upload your latest.log. Services like mclo.gs automatically obfuscate sensitive IP addresses and highlight crash causes.