Facebook app not working!!

please help! I cannot log in using the Facebook app for the past month . Says unexpected error every time. I can log in on my desktop without a problem so I know it is the app.

I have deleted the app multiple times and when I reinstall the app icon always has a number 2 with it (like an unread alert or notification). I have off loaded it and reset my network settings as well. I have no clue what else I can do to fix this. My fb messenger does not work either. Same issue. This all happened when I updated the phone. Please help!!