LOL! Yes, mannekaeng is right.
Although, if you want to be supportive, I'd start with a "Är allt OK med dig?" first, and only then, when the person acknowledges all is not OK, dive into this one...
Is there a way that can help to think more intuitively about this phrase? I keep reading "What is it for wrong about you". The 'för' in particular confuses me.
I know it's wrong, but what would "Vad är fel?" actually mean to a Swedish listener? Something like "What is the nature of wrongness?" Or does it just sound like a jumble of words?
"Vad är fel?" could be used in a context where I have indicated that something is wrong with your text, and you would like to know which bit of it is wrong. Something like "Which bit of this is wrong?" or "Show me what sentence is wrong.".
Or it could be a moral thing: "What is wrong and what is right? = "Vad är fel och vad är rätt?".
The "fault has to lie somewhere": it is "fel på någonting" or "fel med någonting".
I definitely didn't understand that. Where is the adjective? The biggest problem in Swedish learning is the necessity of having lots of prepositions in the same sentence. What is the translation for fel?
Fel is the adjective "wrong," so it is the adjective in the sentence. To my understanding, it can also be the noun "error," but I'm not sure about how to use it in that context.
The situation I thought of: someone does something and almost doews. Me: what is wrong with you?!
This sentance is terrible, you guys need to update this app and fix this stuff