Shopkeeper-version: v2.8.1

Spigot:CraftBukkit version git-Spigot-56f8471-6567017 (MC: 1.14.4) (Implementing API version 1.14.4-R0.1-SNAPSHOT)

I have the problem on my server that shopkeeper sells the decoration heads, the content freezes. You can no longer pull out heads. For shopkeepers with normal items, everything is ok so far.

Likely a spigot or minecraft issue. If I remember it correctly player heads will fetch their texture information occasionally from the mojang servers when viewed. Not sure right now if a plugin can avoid this.

How are those decoration heads created exactly (so that I can try to reproduce this)?

I get my heads with the plugin hdb

https://www.spigotmc.org/resources/head-database.14280/

do you want to come to my 1.15 server? that's where the problem is at the moment

This occurs on 1.14.4 as well as on the 1.15 server

Do you have the 'use-strict-item-comparison' setting enabled?
Also, could you try this again on the latest version of Spigot. There has been an update 2 days ago that fixes some issue related to skull item comparison: https://hub.spigotmc.org/stash/projects/SPIGOT/repos/craftbukkit/commits/82322fe06c1331a4fc0d31b062ed633c99fce004

no I have false. should i activate it?

No, but if it had been true this could have explained it.

o.k maybe the update will help :) I will continue testing. but your snapshot is great so far without any problems :)

but with the update something can happen. I can, although I have restarted the server, take deco heads out without them being frozen, where I had problems before

So this issues is fixed / resolved?
Edit: I can still reproduce this issue with a player head created via: /minecraft:give blablubbabc player_head{SkullOwner:"blablubbabc"}

Edit2: Actually, I was still using an older version of Spigot. With the latest version I cannot reproduce this issue anymore.

I will test it for another 1-2 days after a few restarts and then let you know

I just looked through the code: There seems to be a check that verifies that the result item from the trading view is the expected result item from the trading recipe the trade got created from. This check performs an item comparison using the isSimilar method, which according to the linked commit in Spigot was broken for player head items (for reference: https://hub.spigotmc.org/jira/browse/SPIGOT-5426).
So I am pretty confident that this change in Spigot has fixed this issue.

thank you for the great work