I don't know what to do, so I'll try to ask here.
A couple of friends and me play on a server right now.
My problem is involving Ars Noveau in the modpack above.
Whenever I try to craft a source gem in the imbuement chamber I get following error:
Internal Exception: io.netty.handler.codec.DecoderException: unknown serializer type 91
and get thrown back to the main menu.
Whenever an item goes in the imbuement chamber, be it lapis or amethyst, this error appears.
The problem only comes when source is used in the crafting process. Before that, everything was fine. (just very slow)
It also does not matter if I put it in there, another plyayer, or even a hopper.
Other player I tested it with, did not get the exception.
I tried everything I think could have helped, but nothing worked.