can you try only with vcql installed? I mean
Virtual's Custom Quest Loader
I found the problem!
The problem appears then you do 1.accept quest -> 2. go to charakter -> 3 open quests tab now you see a quest and then the error appears.
Then i do 1. acceppt quest -> 2. COMPLETE quest -> 3. go to charakter ->4. open quest tab and now you see only the normal quests without the error.