Migrated from: https://dev.bukkit.org/projects/shopkeepers/issues/328

Originally posted by MasterMithrandir (Jun 24, 2015):

There seem to be some issues when attempting to trade certain heads generated by the PlayerHeads plugin. Specially Witch and Spider heads.Would be great if some compatibility could be added. Allthough this issue seems to relate to the internal item codes as usual.Shopkeepers version: 1.61
Server version: 1.8.7I've already reported this issue to the PlayerHeads developers.

Originally commented by blablubbabc (Jun 24, 2015):

Maybe this is related to this issue: http://dev.bukkit.org/bukkit-plugins/shopkeepers/tickets/311-when-using-a-head-without-a-name-or-real-uuid/
This issue is about spigot's item serialization not properly saving/loading heads with custom textures (without valid owner).

Originally commented by MasterMithrandir (Jun 25, 2015):

This issue happens whith all heads generated whith PlayerHeads, both giving them through command and just getting them from configured mob drops.

I think it might even happen whith normal vanilla heads... allthough these heads are also managed by PlayerHeads plugin, and I think they might have some differences whith the normally obtained through creative.

Sometimes, but not always, a viable solution is to place the heads on the ground and pick them up. This seems to fix the internal problem and makes the head tradeable.

Originally closed by blablubbabc (Jul 17, 2015)

Originally commented by blablubbabc (Jul 17, 2015):

I will close this ticket, as I assume that this is something which needs to either be fixed in PlayerHeads (if those custom head items could also not be traded in vanilla villagers, setup for example via the vanilla commands in MC 1.8) or in Spigot (if the issue is related to saving/loading the items to config files).

Shopkeepers uses minecraft's default in-built mechanics for handling the trades, and spigot's item serialization for saving and loading the items involved in the trades.