An out-of-memory (OOM) crash happens when your server tries to use more RAM than it has allocated. The system kills the process to protect the node, and your server stops.
Recognizing an OOM Crash
OOM crashes can appear in different ways:
- Console shows “Killed”, “Out of memory”, or similar messages
- Server exits with code 137 (this typically indicates OOM)
- Server stops abruptly with no clear error
- Java-based games may show heap space errors
Check the memory graph on your server’s console page in the Game Control Panel. If memory usage was pinned at maximum before the crash, OOM is likely the cause.
Common Causes
Too many mods or plugins. Every mod and plugin consumes RAM at startup and during operation. Complex mods that add entities, dimensions, or world generation use more than lightweight utility mods.
Large or complex worlds. Older worlds accumulate data over time. Pre-generated terrain, entity-heavy areas, and complex builds all increase memory usage when loaded.
High player count. Each player loads chunks around them and adds entities to track. More concurrent players means more RAM in use.
Memory leaks. Some mods or plugins don’t release memory properly over time. If your server runs fine initially but crashes after hours of uptime, scheduling a daily restart can help. See The Schedule Manager.
Insufficient RAM for the game. Some games and modpacks simply require more RAM than a given plan provides.
Diagnosing the Issue
Start by identifying when crashes occur:
- At startup: Likely not enough RAM for your mods/plugins to load, or the heap size needs adjustment
- During play: Triggered by player activity, chunk loading, or specific game events
- After extended uptime: Suggests a memory leak that accumulates over time
Check the memory graph in the Game Control Panel. If usage climbs steadily without dropping, that points to a leak.
Adjusting Max Heap Size
Some games (including Minecraft and Hytale) have a Max Heap Size or Max RAM Percentage setting in Server Options. This controls how much of your allocated RAM goes to the game versus system overhead.
- If you’re crashing at startup or during heavy load: Try lowering the heap percentage to leave more room for overhead
- If memory usage stays low but you’re still crashing: The heap may be too restricted. Try increasing it.
This setting is found under Server Options in the sidebar. If your game doesn’t have this option, skip to the next section.
Optimization Tips
Before upgrading RAM, try reducing memory usage:
- Remove unused mods and plugins. If you’re not using it, it’s still consuming RAM.
- Reduce view distance or simulation distance. Fewer loaded chunks means less memory.
When to Upgrade RAM
If you’ve adjusted heap size, optimized your setup, and still hit OOM crashes, your server may need more RAM. This is common when:
- Your player count has grown beyond what your current plan supports
- You’ve added mods or plugins that require more resources
- You’re running a game or modpack with high baseline requirements
See Upgrade/Downgrade Your Service for steps, or open a support ticket if you need help.