Tools / Project Zomboid / Fixes
Fix Project Zomboid Out of Memory Crashes
The JVM ran out of heap while loading mods, maps, saves, or player data. Heavy modpacks often need more memory than the default startup script provides.
When this is the problem
- The log contains OutOfMemoryError, Java heap space, or GC overhead limit.
- The crash appears during mod loading, map loading, or shortly after players join.
- A smaller or vanilla server starts normally on the same machine.
Repair steps
- Increase the server -Xmx heap setting; try 6G for moderate modpacks and 8G or more for heavy map/mod stacks.
- Remove the most recent large mod or map pack if memory increased right after adding it.
- Check host memory graphs to confirm the machine has free RAM beyond the Java heap.
- Restart and analyze the fresh log tail to confirm the OOM is gone before making more changes.
Prevent it next time
- Size memory for the modpack, not for vanilla PZ.
- Add large maps and item packs gradually, with one boot test per change.
- Keep backups before memory-related crashes corrupt saves or player files.
Check the fresh log
After changing the server, restart once and analyze the newest log tail. Do not keep debugging the old failed startup log after the config changes.