How to Fix an FTB Skies Server That Keeps Crashing
FTB Skies runs on NeoForge 1.20.1 with Java 17, and several of its most-reported crashes trace back to specific, documented causes rather than a generic skyblock-pack mystery.
See the FTB Skies pack page for boot-tested RAM data before you chase anything else.
1. Client-only mod files left on the server
Some FTB Skies mods are client-only and were never meant to run on the server. Manually copying files from the client pack into the server's mods folder is a documented cause of crashes in this pack.
Fix: use the official server pack as-is rather than hand-assembling a mods folder from the client install.
2. Sky Castle quest crash
The Sky Castle quest has had a reported server crash tied to its completion trigger. If the crash correlates with that specific quest, check your pack version's changelog for a fix before troubleshooting further.
3. Roots mod entity crash entering The End
Some FTB Skies 2 releases have had a crash from a Roots mod entity (SproutEntity) specifically when entering The End. If this matches your symptom, updating to a patched version resolves it directly.
4. Wrong NeoForge or Java version
FTB Skies needs Java 17 and the NeoForge build bundled with the server pack. A mismatch here typically prevents the server from starting at all rather than crashing mid-session.
FAQ
What Java version does FTB Skies need?+
Java 17. FTB Skies runs on Minecraft 1.20.1 with NeoForge, which requires Java 17 — do not use Java 8 or Java 21.
Why does my server crash and the crash log mentions a client-only mod?+
Some FTB Skies mods are client-only and should never be copied into the server's mods folder. If you manually added files from the client pack, remove anything client-side — this has been a documented crash cause in this pack specifically.
A specific quest crashes the server — is that normal?+
The Sky Castle quest has had a documented crash bug. If a crash correlates with a specific quest completion or trigger, check whether it's a known issue for your pack version before assuming it's your server config.
Host FTB Skies on a clean, correctly-configured stack
CoalHost runs the official FTB Skies server pack with NeoForge and Java 17 pre-configured, avoiding the client-only mod trap entirely.
View FTB Skies Hosting →