[MC-68593] Wither will not spawn

This affects the 1.8 Snapshots later than 30a. May be sooner

The wither will not spawn if there are blocks underneath the arms of the T of soul-sand when trying to spawn the wither in any difficulty.

Representation:
W= Wither Skeleton Skull, S = Soul Sand, X = Empty Space,
W W W
S S S
X S X

If there are any blocks in the X spaces the Wither will fail to spawn.
This was also seen in an Episode of Mind-crack Season 5 from sethbling when they were trying to spawn a wither and it wouldn't work as there was tall grass underneath the soul sand. After they moved the soul sand it worked fine as there was nothing underneath the T

Link to Mind-crack episode:
https://www.youtube.com/watch?v=PZQk9YLoCgA&list=UU8aG3LDTDwNR1UQhSn9uVrw

Linked issues

duplicates 1

MC-60792 Iron golems and withers can't be summoned via building them if there are blocks located near their bases or heads Reopened

Comments 3

galaxy_2alex 2014-08-21T11:58:44Z

Duplicate of WAI
MC-60792

Robert Anthony Whitelock 2014-08-21T12:10:07Z

I was Attempting to create a Wither auto-killer with TNT and an obsidian box and when i tried to spawn a wither in a hole in it it wouldn't work. so i want outside the box and tried again and the wither spawned successfully. i decided that there must be a bug as the Wither spawned outside fine with no blocks under the soul sand but in the obsidian box in the hole it wouldn't work as there was obsidian under the soul sand "arms". after further testing i found that it was true with any block. this was confirmed for me in the already mentioned Mind-crack episode when it wouldn't work for them either with the tall grass underneath it.

Robert Anthony Whitelock 2014-08-21T12:15:22Z

Also in 14w30c The Wither would move around to attack things before it exploded after being spawned. i do not know if this was fixed in a later version.