“An unexpected error occurred” when signing in Facebook on Iphone7

When I sign in Facebook on Iphone7 , it show “ an unexpected error occurred.Please try logging in again.” I try to reset all setting and reset network setting but it still cannot log in. I reset all content and setting so I can log in to Facebook but when I restore from backup it still cannot log in. I can log in my Facebook in desktop , other mobile phone normally but cannot in Iphone7.

Pls help ,Thank you