How to Fix a Restless Horizons Server That Keeps Crashing

1. Check your Java version first

Forge 1.20.1 requires Java 17 to run at all, and this is the single most common cause of a server that fails to boot rather than one that crashes mid-session. If your host, control panel, or an old saved launch profile is pointing at Java 8 or Java 11, Forge will fail during startup, often with errors that look unrelated to Java at all. Confirm the server is actually launching under Java 17 before you spend time on anything else.

• Run `java -version` from the same shell/user context the server actually starts under, not just your login shell
• Check your start script or panel's Java runtime setting if the server was migrated from an older pack

2. Dimensional exploration gates causing chunk-load spikes

Restless Horizons is designed around moving between dimensions and biomes to progress, and that design choice has a real server-side cost: the first time any player steps through an exploration gate or wanders into a freshly generated biome region, the server has to generate, populate, and light a large batch of chunks essentially all at once.

This is a well-known pattern in exploration-heavy packs generally, not unique to Restless Horizons — it typically shows up as a multi-second freeze or a sharp TPS drop right as a player crosses into new territory, rather than a crash. On a server that's already near its RAM or CPU ceiling, though, that spike can be enough to push a tick over the watchdog's timeout threshold and take the server down.

3. Combat mods spiking tick cost during encounters

To make the exploration loop meaningful, packs in this category add combat mods that make encounters in new areas genuinely dangerous rather than trivial. Those mods — entity AI, extra mobs, ability/particle effects — add real tick cost, and a fight that spawns a lot of hostile entities at once can produce the same kind of short-lived TPS drop as the chunk-load spikes above, just triggered by combat instead of world-gen.

If crashes or freezes cluster around fights rather than exploration or boot, this is the more likely culprit — worth checking your server log timestamps against when players report the lag happening.

4. Config corruption or a bad mod update after a pack upgrade

If the server booted and ran fine for a while and only started crashing after you updated the modpack version or hand-edited a config file, treat that update as the first suspect rather than reopening the Java or RAM questions above. A corrupted config from an interrupted write, or a mod version bump that isn't compatible with the rest of the pack's locked mod list, is a common way a previously stable Forge server starts crashing on a specific action (entering a dimension, triggering an encounter) instead of randomly.

5. RAM under the pack's realistic floor

The real floor for Restless Horizons is 6 GB, which is what you should size to rather than a generic guess based on the pack's description alone. Running below that floor rarely produces one clean out-of-memory crash — what you'll actually see is a cascading pattern: garbage collection pauses get longer and more frequent as memory pressure builds, TPS drifts down during normal play, exploration and combat spikes (sections 2 and 3) hit much harder because there's no headroom to absorb them, and eventually a tick takes long enough that the watchdog kills the server. If your crashes feel 'random' and loosely correlated with busier moments rather than one specific trigger, undersized RAM is worth ruling out before anything else.