600 - Oops something went wrong, please try again.

[bellabianca]

My brother invited me for premium for family but when I try to activate the code I get "600 - Oops something went wrong, please try again." Who knows what I have to do???

[Demnian]

Yeah I get the same thing. By brother also invited me, but I can't connect due to the same error. Clearning Browser's Cache and Cookies and enabling Compatibility view does not solve it. 

[earlshaker]

Still getting this problem? try changing your address first from your account settings before you accept the invitation.