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GregTech: New HorizonsTroubleshooting

Troubleshooting

Common issues and solutions for GT:NH servers.

Server Won’t Start

Mod Conflicts

Problem: Server crashes during startup with mod errors

Solution:

  1. Check console for error messages
  2. Verify all mods are for correct Minecraft version
  3. Remove conflicting mods
  4. Restore from backup if needed

Java Errors

Problem: Server crashes immediately upon pressing start with various errors

Solution: Create a support ticket and our team will investigate and resolve this.

Connection Issues

Can’t Connect to Server

Checklist:

  • ✅ Server is running (green status)
  • ✅ Using correct IP address (and port, where applicable)
  • ✅ Same modpack version as server
  • ✅ Not IP banned or not whitelisted
  • ✅ Firewall not blocking connection

Timeout on Connection

Usually caused by:

  • Server overloaded (check TPS)
    • If you have Spark installed (Reizor Hosting servers created or updated after December 9th, 2025 have Spark automatically installed), run /spark tps
    • Otherwise, run /forge tps

In the event your TPS looks shaky, you can use Spark to diagnose what may be causing TPS issues. See Spark’s guide on using the profiler and tickmonitor .

  • Network issues
    • For help diagnosing this, reach out to our support team and we can help walk you through diagnosis steps.
  • Out of memory
    • If your server runs out of memory, it will entirely lock up until given more memory or is killed manually via the panel.

Performance Issues

Low TPS (Anything Below 20)

Causes:

  • Too many machines
  • Too many entities
  • Inefficient automation setups
  • Certain machines being used that are innately laggy.

Solutions:

High RAM Usage

Out of Memory Error

Problem: Server crashes with OutOfMemoryError (or is automatically killed by the out of memory killer)

Solution:

  • Investigate potential memory leaks
    • As of 2.7.1 and later, there is a large memory leak that occurs from rapidly switching dimensions
    • As of 2.8.0 and later, there are various memory leaks caused by rapid exploration
  • Restart the server more frequently to free up leaked memory

Monitor RAM in panel:

  1. Clear unnecessary entities
  2. Reduce view distance

World Corruption

Recovering from Corruption

  1. Stop the server
  2. Go to Backups tab
  3. Restore from latest working backup
  4. Restart server

Preventing Corruption

  • Enable automatic backups
  • Graceful shutdowns (use Stop, not Kill)
  • Keep backups of important progress

Getting Additional Help

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