❗Common Issues

You can find common issues listed here

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1. Java Issues

Console Message:

Error: A JNI error has occurred, please check your installation and try again.
Exception in thread "main" java.lang.UnsupportedClassVersionError: net/minecraft/server/MinecraftServer has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 55.0

or the following message immediatelly after starting the server:

The server either closed or crashed...
The server will restart after the countdown, please close this window to stop the server completely.

Explanation: This error means that the Minecraft server requires a newer version of Java, typically Java 21 for Minecraft 1.21 and above, but your system is running an older version like Java 8 or Java 11.

Solution (for Windows):

1. Download Java 21:

   • Go to the Oracle Java SE Downloads and download the Windows Installer for Java 21.

2. Install Java:

   • Run the installer and follow the prompts to install Java 21 on your system.

3. Verify Java Version:

   • Open Command Prompt and type:

     java -version

     It should return something like java version "21.0.x".

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2. Insufficient Resources

Console Message:

[17:22:31 ERROR]: Exception in server tick loop
java.lang.OutOfMemoryError: Java heap space
    at net.minecraft.server.MinecraftServer.loadWorld(MinecraftServer.java:721)
    at net.minecraft.server.dedicated.DedicatedServer.init(DedicatedServer.java:305)
    ...

Explanation: This error occurs when the server doesn’t have enough RAM to function. By default, the server may allocate only 1GB of RAM, which is insufficient for larger servers, modded worlds, or multiple players.

Solution (for Windows):

1. Modify the Server Startup Script:

   • Open the start.bat file (or create one if it doesn’t exist) in your server folder.

   • Edit the file to allocate more memory by changing the -Xmx and -Xms parameters:

     java -Xmx4G -Xms2G -jar server.jar

     Here, -Xmx4G sets the maximum RAM to 4GB, and -Xms2G sets the initial allocated RAM to 2GB.

2. Ensure Sufficient System Memory:

   • Right-click This PC > Properties and check how much RAM your system has. Make sure the server’s allocated RAM doesn’t exceed your system's total available memory.

3. Command Line Check:

   • If the server still crashes, open Command Prompt and run:

     tasklist | findstr java

     This will show how much memory the Minecraft server is using in real time.

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3. Port Already in Use

Console Message:

[17:22:31] [Server thread/WARN]: **** FAILED TO BIND TO PORT!
[17:22:31] [Server thread/WARN]: The exception was: java.net.BindException: Address already in use: bind
[17:22:31] [Server thread/WARN]: Perhaps a server is already running on that port?

Explanation: This error means that another application (or another Minecraft server instance) is already using the default server port (25565). A port can only be used by one process at a time.

Solution (for Windows):

1. Check for Other Processes Using the Port:

   • Open Command Prompt as Administrator and run the following command to see if any process is using port 25565:

     netstat -aon | findstr :25565

     This will list any processes using port 25565. The last number is the PID (Process ID).

2. Terminate the Conflicting Process:

   • If a process is using the port, find it by running:

     tasklist | findstr <PID>

   • Terminate the process by running:

     taskkill /F /PID <PID>

3. Change the Server Port:

   • If you cannot free up port 25565, open the server.properties file and change:

     server-port=25566

   • Save the file and restart the server.

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4. Firewall or Network Issues

Console Message:

[17:22:31 INFO]: /192.168.1.101:54321 lost connection: Timed out

Explanation: This error means that a player was unable to connect to your server. It could be due to your firewall blocking connections or incorrect port forwarding. On a local machine, firewalls sometimes block external traffic from reaching the server.

Solution (for Windows):

1. Allow Minecraft Server Through Windows Firewall:

   • Open Control Panel > System and Security > Windows Defender Firewall > Allow an app or feature through Windows Defender Firewall.

   • Find javaw.exe in the list and ensure it's allowed for both Private and Public networks. If it's not there:

     • Click Allow another app > Browse > navigate to your Java installation folder (C:\Program Files\Java\jdk-21.x.x\bin) and select javaw.exe.

2. Port Forwarding (for home routers):

   • Open your router settings (usually accessed via a browser at 192.168.1.1).

   • Go to Port Forwarding settings and forward port 25565 (or whichever port your server uses) to your machine’s local IP (e.g., 192.168.1.101).

   • Set both TCP and UDP protocols for this port.

3. Verify Your Public IP:

   • If you are hosting the server on a home network and allowing external players, provide them with your public IP. You can check your public IP by visiting WhatIsMyIP.

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5. Incorrect EULA

Console Message:

[17:22:31 INFO]: You need to agree to the EULA in order to run the server. Go to eula.txt for more info.

Explanation: The Minecraft server requires you to accept the End User License Agreement (EULA) before it can start. If eula=false in the eula.txt file, the server won’t run.

Solution (for Windows):

1. Open the eula.txt file in the server directory using Notepad.

2. Change the line:

   eula=false

   to:

   eula=true

3. Save the file and restart the server.

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Sure! Here’s the updated guide with additional sections covering Minecraft plugin errors and general Minecraft server errors that often occur with plugins or mods.

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6. Plugin Errors

6.1. Incompatible Plugin Version

Console Message:

[17:22:31 ERROR]: Could not load 'plugins/WorldEdit.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: Unsupported API version 1.20
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:132)
    at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:398)
    ...

Explanation: This error occurs when a plugin is designed for a different version of Minecraft than the server is running. For example, the server might be running Minecraft 1.18, but the plugin was made for Minecraft 1.20.

Solution (for Windows):

1. Check Plugin Compatibility:

   • Go to the plugin’s page (usually on sites like SpigotMC or Bukkit) and verify which Minecraft versions the plugin supports.

2. Download the Correct Version:

   • If an older or newer version of the plugin is available for your Minecraft version, download that version and place it in the plugins folder.

3. Update the Server:

   • If you prefer to use the newer plugin version, consider updating your server to match the plugin’s version. Always ensure your plugins and server are compatible.

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6.2. Missing Dependencies

Console Message:

[17:22:31 ERROR]: Could not load 'plugins/EssentialsX.jar' in folder 'plugins'
org.bukkit.plugin.UnknownDependencyException: Vault
    at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:219)
    ...

Explanation: This error occurs when a plugin requires another plugin (known as a dependency) to function, but the dependency is not installed. In this example, the EssentialsX plugin requires Vault to be installed.

Solution (for Windows):

1. Identify the Missing Dependency:

   • Check the error log to find out which dependency is missing (e.g., Vault in the above error).

2. Download the Dependency:

   • Go to the plugin repository (e.g., Vault) and download the latest compatible version of the missing plugin.

3. Install the Dependency:

   • Place the downloaded plugin in the plugins folder.

   • Restart your server to load the new dependency.

4. Check Plugin Documentation:

   • Some plugins require additional configuration or dependencies. Always review the plugin’s official documentation to ensure all necessary dependencies are installed.

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6.3. Plugin Configuration Error

Console Message:

[17:22:31 ERROR]: Could not pass event PlayerJoinEvent to MyPlugin v1.0
org.bukkit.event.EventException: null
    at org.bukkit.plugin.EventExecutor$2.execute(EventExecutor.java:72)
    ...
Caused by: java.lang.NullPointerException
    at myplugin.MyPlugin.onPlayerJoin(MyPlugin.java:42)
    ...

Explanation: This error occurs when a plugin encounters an issue during runtime, often due to an incorrect configuration file, missing settings, or a code issue within the plugin itself.

Solution (for Windows):

1. Check the Plugin’s Configuration:

   • Open the plugin's configuration file (usually located in the plugins/<plugin_name> folder).

   • Look for any errors, missing fields, or invalid values.

2. Revert to Default Config:

   • If you’re unsure about the correct settings, delete the configuration file and restart the server. The plugin will generate a fresh default configuration file.

3. Check for Plugin Updates:

   • If the error persists, visit the plugin’s page and check if there’s an update or patch that fixes the issue.

4. Report the Issue:

   • If it seems like a plugin bug, report the error to the plugin developer, providing the error message and steps to reproduce.

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7. General Minecraft Errors

7.1. Corrupted World Files

Console Message:

[17:22:31 WARN]: Chunk file at 45, 12 is in the wrong location; relocating. (Expected 45, 12, got 44, 11)
[17:22:31 ERROR]: Couldn't load chunk at 45, 12
java.io.IOException: Corrupted world data
    at net.minecraft.server.level.chunk.ChunkProvider.load(ChunkProvider.java:421)
    ...

Explanation: This error occurs when one or more chunks in your Minecraft world become corrupted, often due to improper shutdowns, crashes, or disk errors. The server can’t read the chunk data properly, which can cause issues when loading the world.

Solution (for Windows):

1. Backup Your World:

   • Before trying to fix the issue, make a backup of your world folder by copying it to a safe location.

2. Use MCEdit to Repair:

   • Download and install MCEdit (a world editing tool for Minecraft).

   • Open your world in MCEdit and locate the corrupted chunk. Delete or repair the chunk, and save the world.

3. Delete the Corrupted Region File:

   • Minecraft worlds are divided into region files, each containing a large set of chunks. Find the region file corresponding to the corrupted chunk and delete it. The server will regenerate it automatically:

     • World region files are located in world/region/ and have names like r.x.z.mca. Use an online tool like ChunkBase to find the region containing the corrupted chunk.

4. Restore From Backup:

   • If repairing doesn’t work, restore the world from a previous backup before the corruption occurred.

7.2. Corrupted Server Files

Console Message:

[17:22:31 ERROR]: Failed to load properties from file: server.properties
java.io.FileNotFoundException: server.properties (The system cannot find the file specified)

Explanation: This error occurs when the server.properties file is missing or corrupted. This file controls many of the server’s settings, such as world name, game mode, and server port.

Solution (for Windows):

1. Recreate the server.properties File:

   • If the file is missing, you can manually create a new server.properties file in the server folder. Use a basic text editor like Notepad and input the default settings. Alternatively, starting the server without a server.properties file should automatically generate a new one.

2. Verify File Integrity:

   • If the file is corrupted, open the file and inspect it for any unusual characters or missing lines. You can also compare it with the default server.properties configuration from the Minecraft wiki or re-download it from the official Minecraft server files.

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7.3. "Internal Server Error" on Player Join

Console Message:

[17:22:31 ERROR]: Player lost connection: Internal Server Error
java.lang.NullPointerException: Cannot invoke "net.minecraft.server.level.EntityPlayer.d()" because "<parameter>" is null

Explanation: This error often occurs when a player tries to join a server that has an issue with plugins, mods, or corrupted player data, resulting in the server disconnecting them due to an internal error.

Solution (for Windows):

1. Check for Plugin or Mod Conflicts:

   • Disable any newly installed or recently updated plugins or mods. You can do this by temporarily moving them out of the plugins or mods folder and restarting the server to see if the issue is resolved.

2. Clear Player Data:

   • If the issue seems specific to a player, you can reset that player’s data by deleting their player data file from the world/playerdata/ folder. Be sure to make a backup of this file before deleting it.

3. Review Logs:

   • Check the server logs in the logs/latest.log file for more detailed information about what caused the error.

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If the issues are not resolved, feel free to contact me on BuiltByBit.