I have built a mob farm in my single player world, but it doesn't work.

I have tested the mob farm in a super flat world and it works well. I have built them almost identical, the only difference is that I used snow blocks instead of cobble and that half my mob farm is built in a deep ocean biome and the other half is in an ocean biome. I have checked and there is no light in the farm and no caves under it. I have searched for an asnwer but nothing seems to work.

I copied the farm from logdotzips 34th episode of how to minecraft.

  • 1
    You say they're identical except X and Y are different. Try making them identical and see what you get. Jul 16, 2015 at 16:42
  • Thanks. If tried but I beleive the design isn't working.
    – Ethan
    Jul 16, 2015 at 18:24
  • If you suspect there is a problem in the design, it would be very helpful to include references to that design; say with pictures from minecraft or similar. If you got the design from a website, it may be useful to include that as well. In the meantime, after you do this and while you wait for answers, you may find some very useful information here: minecraft.gamepedia.com/Spawn#Spawn_cycle ; especially under 'Spawn conditions'
    – Bob2Chiv
    Jul 16, 2015 at 18:50
  • I copied the farm from logdotzips 34th episode of how to minecraft.
    – Ethan
    Jul 16, 2015 at 21:31

2 Answers 2


The Problem
The problem that you had is because of the cave underground / near the mob farm. Why superflat world worked? Simply because there is no cave under / below it.

Why is it? It's because when a mob want to spawn, the game simply search for a random location with certain requirement needed. In this situation is Light Level.

How to fix it
Well simply enough, you must make the light level of near by caves up. You can see the block you're standing light level by entering the Debug Menu by pressing F3. Make sure there is no near by cave to have light level of 7 or below. Make sure also there is no cave with light level 7 or below in 64 block from the middle of the farm.


I would suggest using the Monster Cobble. I usually play on creative and theres a stone that spawns monsters.

You could try building it out of that?

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