Monk Quest "Good Vibrations" doesnt allow me to progress

Time: permanently
Frequency: constant
World name: Ultros
Character name: Ragefist Angerknuckle
NPC name: Erik
Class/Level: Monk/45
Area and coordinates: Uldah Goldsmith guild (10-13)
The quest name is "Good Vibrations".

I got my Monk to 45 so I started the questline to get the class armor.
I finished the part where you actually get all the armor pieces. I put them on and then continued with the quest.
I got sent to Uldah to completely wrap it up, but when I arrived I got the error message "Unable to accept the melee circlet. You can only carry one of this item.".
Thats where I'm stuck. I cant abandon the quest to try it again, and I even discarded the Monk armor to see if it would change anything about the error message, but it didnt.

Now I'm standing around naked in Uldah and I cant progress with the story.
Please help