How to Fix a Zombie Invade 100 Days Server That Keeps Crashing
Zombie Invade 100 Days is the Forge Labs 100 Days zombie apocalypse remade for modern Minecraft on Forge 1.20.1 — 14.5M+ downloads and the single most-downloaded pack in our catalog. Its most common crash cause isn't a mod conflict; it's a RAM floor that's genuinely higher than the number most players expect.
See the Zombie Invade 100 Days pack page for the full RAM and setup breakdown before you chase anything else.
1. The 8 GB minimum is disproven — use 12 GB
A commonly cited 8 GB minimum for this pack does not hold up under real testing: direct re-probing showed the JVM getting OOM-killed (exit 137) during first boot at 8 GB on every restart attempt. A 12 GB re-probe passed minutes later. If your server crashes right at boot or very early and you're running 8 GB, raise it to 12 GB before investigating anything else.
2. Server won't boot at all: check the Java version
Separately from the RAM issue, Forge on Minecraft 1.20.1 requires Java 17. A server on an older Java runtime will fail consistently at startup.
- Confirm the server is launching under Java 17, not an older runtime
3. Escalating horde tick spikes later in a run
The pack's defining mechanic is a 100-day survival arc with escalating zombie hordes — later days throw larger, more aggressive waves than early ones. A server that was stable through the early game can start showing real lag purely because the horde difficulty has scaled up, not because of a new bug.
4. Config corruption or a bad mod update after a pack upgrade
If the server ran fine and only started crashing after updating the modpack version or hand-editing a config, treat that update as the first suspect rather than reopening the RAM or Java questions above.
FAQ
Why does my server get OOM-killed at RAM levels that 'should' be enough?+
This pack's commonly cited 8 GB minimum doesn't hold up under real testing — we've directly measured the JVM getting OOM-killed (exit 137) during first boot at 8 GB, on every restart attempt. 12 GB is the floor that actually passes boot testing consistently. If you're running at 8 GB and seeing crash-on-boot, this is almost certainly why.
Why does my server fail to boot entirely, separate from the RAM issue?+
Zombie Invade 100 Days runs on Forge for Minecraft 1.20.1, which requires Java 17. A server on an older Java runtime will fail at startup before RAM is even a factor.
Why does my server lag as the horde escalates over the 100 days?+
The pack's core mechanic is escalating zombie hordes over a 100-day survival arc — later days throw larger, more aggressive hordes than early days. A server that handled day 10's horde fine can start struggling by day 60 purely because the horde itself has scaled up, not because anything is broken.
Host Zombie Invade 100 Days on the floor that actually boots
We size this pack at a measured 12 GB, not the lower number that OOM-kills on first boot, and take a backup before day 100 so a late-game crash never costs the whole run.
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