You must enter both username and password

Is this an english language issue? There is nowhere to enter username....

Dialog prompts for PASSWORD.

Options are "Cancel", "Sign In" and "Forgot Password"

I know the passwords of all accounts on the device - just need to know which appleid is requesting auth.

Simple solution : please give a hint for the appleid for which the password is being prompted.

P.S. is this a generic ios problem regardless of device?