Facebook session has expired on iPhone app?

I deleted the app yesterday so I could update the software on my iPhone. When I downloaded it again it would not let me log in to Facebook or Facebook messenger saying 'your Facebook session has expired, please login again'. I've tried logging in so many times and I've tried deleting the app, turning my phone off, I've even tried the whole thing with deactivating my account and reactivating it. Can anybody help me?

Try And See if You Can Get On Using the Mobile Site Or The Desktop Site if it Works On The Desktop Site or The Mobile Site Then it May Be a Bug With The Facebook App

Please Contact Facebook At The Help Center and Report the Problem To Them