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Spawn Doctor

Spawn Doctor

/spawndoctor — plain-language diagnosis of why your mob farm isn't spawning anything (Peaceful, doMobSpawning, cap theft, AFK ring, sim distance).

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Compatibility

Minecraft: Java Edition

1.21.1
1.20.1

Platforms

Supported environments

Server-side
Singleplayer

Links

Report issues View source

Tags

Creators

Details

Licensed MIT
Published 4 days ago

Spawn Doctor

You built the mob farm exactly like the tutorial and nothing spawns. /spawndoctor tells you why — in plain words.

"Built it like the tutorial, nothing spawns" is one of the most repeated cries on r/Minecraft, r/feedthebeast and Aternos. Existing spawn overlays only show light level — none explain why a correctly-built farm produces nothing (cap theft from far-loaded mobs, AFK ring, sim distance). That's the gap this fills.

  • 🩺 One command, plain-language diagnosis — not a flame graph, not an overlay
  • 🎯 Calls out the dead-certain causes: Peaceful difficulty, doMobSpawning off
  • 🕳️ Surfaces the #1 silent killer: hostiles loaded far away eating the spawn budget your farm needs
  • 📏 Always-shown spawn rules: the 24–128 ring and the server's simulation distance

What it does / Usage

Stand where you expect spawns, run /spawndoctor:

Spawn Doctor — why your mob farm is dead:
42 hostile mobs are loaded FAR from you vs only 3 nearby. The far ones eat
the same spawn budget your farm needs — light up caves / clear them.
 ┃ Mobs spawn 24-128 blocks from a player: AFK at least 24 blocks away…
 ┃ Server simulation distance: 10 chunks — the farm must be within that…

Open to all players; 30s cooldown (ops bypass).

Supported loaders / versions

Minecraft NeoForge Forge Fabric
1.21.1 ✅ ✅ ✅
1.20.1 — ✅ ✅

Ships for NeoForge / Forge / Fabric on Minecraft 1.21.1, and Forge / Fabric on Minecraft 1.20.1 (NeoForge has no 1.20.1 build). Server-side, dependency-free, identical behaviour on every loader.

Dependencies

None.

Compatibility & scope

Read-only, on-demand, server-side. No mixin, no config, no blocks/items — can't conflict with other mods.

Known limitations

The mob-cap formula is version-sensitive and easy to get wrong, so Spawn Doctor never claims an exact "cap X/Y" — a wrong number is worse than none. It reports the certain, explanatory facts (the cap-theft framing is true regardless of the exact cap) plus the universal spawn rules.

Install

  1. Install your mod loader — NeoForge, Forge, or Fabric — for Minecraft 1.21.1 or 1.20.1.
  2. Drop spawndoctor-0.1.0.jar into mods/. Server-side.
  • Minecraft 1.21.1 · NeoForge · JDK 21

Languages

Output localized in 9 languages (machine-baseline; native-speaker PRs welcome).

License

MIT — modpack inclusion welcome, no credit required.

Author: KURONAMI