I have a tower with a trench around it. Suspended in the walls by signs I have pockets of lava. The intent was to have mobs fall in the trench, try to get me in my basement and eventually touch the lava and catch on fire. This they do, but they do not die.

I am running a mod-less server v1.5 Beta (So clearly this is an SMP game :))

I had two creepers, two zombies and a skeleton in the trench. They would catch on fire when trying to run into the wall with a lava block on it, but never die. They just sit there on fire until they move away from the block.

Is this supposed to be happening? Is this an SMP only bug? Looking for some guidance :)

  • Odd...vanilla server?
    – Bobby
    Apr 26, 2011 at 20:55
  • Yup, no mods anywhere in sight.
    – James
    Apr 26, 2011 at 20:58
  • I'd need to check the mob trap of my brother to see if lava still does what it promises...hold on. I'll check.
    – Bobby
    Apr 26, 2011 at 21:00
  • Well, there was nothing in the trap, but on my way there I successfully killed a zombie with a bucket of lava (and learned that rails get destroyed by lava...I just had finished that damn track :( ). So everything's working for me, though it's a Bukkit-Server with just one plugin (SaveStopper). Do you have version 1.5_02?
    – Bobby
    Apr 26, 2011 at 21:09
  • Edited question with more clarity to your questions
    – James
    Apr 26, 2011 at 21:14

3 Answers 3


The only mobs that are not affected by lava are pigmen and ghasts (though they can drown in it).

  • The mobs are not directly in the lava, they are just touching it so they ignite themselves, however it is becoming apparent that this is just a visual effect and does not actually cause any damage like it does to players.
    – James
    Apr 29, 2011 at 16:35

So, this was noticed way back before release (0.8.0 or so if I recall correctly). I have attempted to reproduce this situation in the latest release as it stands now (1.2.3) and have not been able to get it to happen.

I am not sure if this is because of the fixes that were put in to where you could not longer catch on fire by being on just the right side of a block of lava, or if because the new AI stops them from constantly trying to push their way through solid blocks.

After several attempts with zombies and skeletons I was only ever able to get one skeleton to catch on fire and if I had to lay money I would say what happened was one of its arrows that hit the lava and caught fire, actually bounced back and hit the skeleton, catching it on fire that way.

Since it appears to no longer be able to catch NPCs on fire with out them actually going into the lava, I am going to chalk this up as a bug that has since been fixed, either directly or by coincidence.


Mobs die when they are exposed to lava. This feature works in SMP. This is not a bug or glitch. This may be a problem or just lag with your server.

  • 1
    Same comment as given to TheCommunistDuck, I am not submerging them in lava, they are touching it to become on fire. It just seems that this does not damage mobs like it does when I player is engulfed in flame by touching lava.
    – James
    Apr 29, 2011 at 16:37

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