Minecraft Wiki talk:Issues/1.2.5

Mobs glitching above fence tops
In SMP, at least, mobs can jump onto the top of a fence, and/or pretend to get out (as seen by clients). If the server keeps running, however, they will return to their pen.

But they can also jump up on the edge of a fence. If the server is stopped with them in the air, they appear to get their location saved as in the air, and on server restart can walk off the fence post out of the pen.

That's the observed behavior: starting up a server, logging on, and seeing mobs turning in circles on top of a fence, and deciding to come down out of the pen. Is this an SMP only bug (as I'm going to mark it on the bug page), or does this reproduce in SSP as well?

Keybounce 07:59, 5 April 2012 (UTC)
 * You are actually describing 3 separate bugs. The first bug is mobs appearing to stand on fences or even walk ouside. This bug is MP only. The second one is animals spawning on the fence when a chunk is loaded. This bug also exists in SP. The third one is mobs chasing tails, so to speak, whenever their y coordinate is not an integer (e.g. when standing on slabs or fences, or even when falling. —Fenhl 08:29, 5 April 2012 (UTC)