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Mod & Plugin Issues

Troubleshoot problems with mods and plugins on your server.

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Plugin Issues (Bukkit/Spigot/Paper)

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Plugin Not Loading

Console shows: 
[ERROR] Could not load 'plugins/PluginName.jar'
Common causes:
  1. Wrong server version - Plugin needs updating
  2. Missing dependencies - Install required plugins
  3. Corrupted file - Re-download plugin
  4. Wrong server type - Needs Spigot but running Paper
Solutions:
  1. Check plugin’s required Minecraft version
  2. Install all dependencies listed on plugin page
  3. Download fresh copy from official source
  4. Verify server type compatibility

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Plugin Loaded But Not Working

Check these:
  1. Is it listed in /plugins? (Green = enabled)
  2. Do you have permission to use it?
  3. Is configuration correct?
  4. Any errors in console?
Solutions:
  1. Check plugin documentation
  2. Grant permissions: /lp user <name> permission set <perm> true
  3. Review and fix config files
  4. Update to latest version

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Plugin Causing Crashes

Identify the culprit:
  1. Check crash log for plugin name
  2. Remove plugins one by one
  3. Use Spark to profile
Fix:
  1. Update the plugin
  2. Check for conflicts
  3. Report to plugin developer
  4. Find alternative plugin

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Plugin Conflicts

Symptoms:
  • Features not working
  • Errors mentioning multiple plugins
  • Unexpected behavior
Solutions:
  1. Check known incompatibilities
  2. Update all plugins
  3. Remove duplicate functionality
  4. Use conflict resolution plugins

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Mod Issues (Forge/Fabric)

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Mod Not Loading

Console shows: 
[ERROR] Mod [name] requires [dependency]
[ERROR] Mod [name] (version X) is not compatible
Common causes:
  1. Wrong Minecraft version - Mod version mismatch
  2. Wrong mod loader - Fabric mod on Forge
  3. Missing dependencies - Required mods not installed
  4. Corrupted file - Download corrupted
Solutions:
  1. Download correct mod version for your MC version
  2. Use correct loader (Forge OR Fabric, not both)
  3. Install all required mods
  4. Re-download from official source

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Server Crash with Mods

Diagnosing:
  1. Check crash-reports folder
  2. Look for mod name in stack trace
  3. Check latest.log for errors
Common fixes:
  1. Remove problematic mod
  2. Update mod to latest version
  3. Check for known conflicts
  4. Reduce number of mods

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Client-Server Mod Mismatch

Error: 
Mod [name] is not installed on this client
Version mismatch: server has X, client has Y
Solution:
  1. Ensure exact same mods on server and client
  2. Match versions precisely
  3. Share mod list with players
  4. Use modpack for easier sync

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Mod Configuration Problems

Symptoms:
  • Mod features not working as expected
  • Default values not appropriate
Solutions:
  1. Stop server
  2. Find config in /config/ folder
  3. Edit configuration file
  4. Start server

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Common Error Messages

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”Unsupported major.minor version”

Cause: Wrong Java version Solution:
  • Minecraft 1.17-1.20.4: Java 17
  • Minecraft 1.20.5+: Java 21
  • Contact support to change Java

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”NoClassDefFoundError” / “ClassNotFoundException”

Cause: Missing dependency or incompatible version Solution:
  1. Check what class is missing
  2. Find which mod provides it
  3. Install the dependency

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”Duplicate Mod” Error

Cause: Same mod installed twice Solution:
  1. Check mods folder for duplicates
  2. Remove older/duplicate version
  3. Keep only one version

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”Mixin Error”

Cause: Mod conflict at code level Solution:
  1. Often caused by incompatible mods
  2. Check mod compatibility
  3. Remove one of conflicting mods
  4. Report to mod authors

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Best Practices

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For Plugins

  1. Only install what you need
  2. Download from trusted sources (SpigotMC, Modrinth)
  3. Keep plugins updated
  4. Read documentation before installing
  5. Test on backup server first

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For Mods

  1. Verify version compatibility
  2. Install dependencies first
  3. Use modpacks for easier management
  4. Keep mod list documented
  5. Regular backups before changes

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Troubleshooting Steps

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1. Isolate the Problem

1. Remove all mods/plugins
2. Add back one at a time
3. Test after each addition
4. Identify which causes issue

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2. Check Compatibility

  • Minecraft version match?
  • Mod loader match?
  • Dependencies installed?
  • Known conflicts?

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3. Gather Information

For support requests, provide:
  • Full console/crash log
  • List of mods/plugins
  • When issue started
  • What you’ve tried

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Getting Help

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Resources

  • Plugin’s wiki/documentation
  • Plugin’s Discord/support
  • Mod’s CurseForge/Modrinth page
  • Community forums

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Contact Support