Project Zomboid B42 — Server Fails to Start (Out of Memory)

Summary

On Project Zomboid Build 42 (B42), servers with 8GB RAM or less may fail to start with a Java Memory Error. This is caused by an overly aggressive default Java heap allocation, not corruption or mods.

Affected Systems

• Project Zomboid Build 42
• Servers with 8GB RAM or less

The Cause

B42 ships with -Xmx8g in ProjectZomboid64.json, which tries to allocate 8GB of Java heap — leaving nothing for the OS and other processes.

Solution

1. Go to Files tab in your panel
2. Edit ProjectZomboid64.json in the root folder
3. Find the line "-Xmx8g"
4. Change it to a lower value based on your RAM:
   • 8GB server → -Xmx6g
   • 6GB server → -Xmx4g
   • 4GB server → -Xmx3g
5. Save and restart the server