Minecraft: the server crashes from lack of RAM (OutOfMemoryError)

The java.lang.OutOfMemoryError: Java heap space error in the console means the JVM has exhausted its allocated memory. The server freezes and then restarts.

Cause / The problem

Either the allocated RAM (-Xmx) is too small for the number of players and mods, or it’s too high relative to the plan’s total RAM (the system kills the process via the OOMKiller).

Solution

1. Increase -Xmx in the Pelican panel → Startup tab → Server Memory Limit field. Set the value based on your server:
   • Vanilla / 10 players: 2-3 GB
   • Paper / 30 players: 4-6 GB
   • Heavy modpack: 6-10 GB
2. Never exceed 80% of the plan’s RAM. Keep 1 to 1.5 GB for the system and the JVM itself. On an 8 GB plan, allocate 6 GB at most.
3. Align Xms with Xmx. Having -Xms = -Xmx avoids heap-resizing pauses. Aikar’s flags recommend this equality.
4. Use Aikar’s flags to optimize the garbage collector. Grab them from docs.papermc.io/paper/aikars-flags and paste them into the panel’s JVM Arguments field, adjusting the Xmx and Xms values.
5. Cut consumption if you can’t add more RAM:
   • Lower view-distance (immediate 1-2 GB saving).
   • Reduce the number of preloaded chunks.
   • Limit the heavy mods/plugins identified with Spark.
6. Detect a memory leak. If RAM usage climbs continuously to a crash despite having enough memory, a plugin is leaking. Profile with /spark health to see the curve.

Keep an eye on RAM in the panel: it should oscillate and drop after each garbage collection, not climb steadily.