Yeaaah, it's only a small step: this sould at the end work on mozilla

I performed a bit more testing.
Unfortunately, I tried to login, and seems that login/register is not working here. - chromium (iron) to be precise is throwing error: Unsafe heder "X-JSON"

I dont know the mechanism of this... I tried googling a bit, but no success. Could anyone help me with this one? Why is this eeror thrown when a network activity is performed?