How to Fix a Skyward Colonies Server That Keeps Crashing
Skyward Colonies combines Eureka airships, Create machinery, and MineColonies on Forge 1.20.1, which means a server has three separate simulation systems — flight physics, factory automation, and colonist AI — all competing for tick time at once. Most crash reports trace back to one of a few well-known patterns rather than a single mystery bug: a Java version mismatch at boot, or tick lag from colonies and contraptions compounding until the server times out.
See the Skyward Colonies pack page for the full RAM and setup breakdown before you chase anything else.
1. Check your Java version before anything else
Forge 1.20.1 requires Java 17 — this is the single most common cause of a server that fails to boot at all, and it's the first thing to rule out before assuming a mod conflict. If your server was set up on an older Java runtime, or a host auto-provisioned Java 8 or 11 for it, the server process will fail to start or crash immediately after loading Forge.
- Confirm the server is launching with Java 17, not Java 8 or 11
- Check the startup log for a version-mismatch error near the very top
2. MineColonies tick cost scales with colony size
MineColonies drives a meaningful share of ongoing server load, and that load grows with how many colonists and buildings you've got active — the same pattern seen on other colony-building packs. Pathfinding, AI work-order assignment, and building simulation all run every tick, so a large, mature colony costs noticeably more than a fresh one.
If lag or crashes started appearing as your colony grew rather than at launch, colonist count is a reasonable first suspect.
3. Create contraption lag compounds on top of that
Create's machinery and moving contraptions add their own per-tick simulation cost, and in a pack that pairs Create with MineColonies, that cost stacks directly on top of colony tick load rather than replacing it. This Create-plus-colony compounding effect is a known pattern on other packs that fuse the two mod categories, and Skyward Colonies follows the same shape.
4. Eureka airship physics add a third, separate tick cost
Flying structures and airship physics from Eureka are simulated independently of ground-based colony and factory logic, which means they're worth ruling out on their own rather than assuming every lag spike is colony- or Create-related. If TPS dips specifically when airships are moving or when several are airborne at once, that points at airship simulation rather than MineColonies or Create.
5. RAM under the pack's realistic floor
7 GB is the real floor for Skyward Colonies once airships, a working colony, and Create machinery are all active simultaneously. Under-provisioning rarely produces a clean, instant crash — it usually shows up first as cascading lag and longer garbage-collection pauses as all three systems compete for heap, and that degradation eventually escalates into a full tick timeout and a crash that looks unrelated to RAM at first glance.
FAQ
Why does my Skyward Colonies server crash right on boot?+
The most common boot-time failure on Forge 1.20.1 packs is simply running the wrong Java version — Forge 1.20.1 needs Java 17, and launching with Java 8 or 11 will fail to even load the mod list. Check your server's Java version first before digging into anything else.
Is MineColonies or Create the bigger performance cost in Skyward Colonies?+
Both contribute, and they stack. MineColonies colonist AI and pathfinding scales with your colony size the same way it does in other colony-building packs, while Create's contraption simulation adds its own per-tick cost once factories get large. If TPS drops as colonies and factories grow in parallel, you're likely seeing both at once rather than a single culprit.
How much RAM does a Skyward Colonies server actually need?+
7 GB is the realistic floor for Skyward Colonies once you have active airships, a MineColonies town, and Create machinery running. Going below that doesn't usually cause an instant crash — it shows up first as rising GC pauses and lag spikes that eventually escalate into a tick timeout.
Host Skyward Colonies on hardware sized for its real floor
Skyward Colonies needs a genuine 7 GB floor once airships, colonies, and Create factories are all running — and automated backups before any risky colony or factory change mean a bad build never costs you the whole world.
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