I Updated Facebook and now It Won't Work
Edit: this appears to be a concern that Facebook recognize. It's an issue with the Facebook app, and not a generalised Play Store issue.
This is what worked for me at the very least.
- Settings > Applications > All > Google Play Store, Clear data and Clear cache
- Settings > Applications > All > Google Play Solutions > Manage room, Clear all data and Clear cache
It doesn't hurt if you reactivate your phone prior to you attempt updating facebook once more. As well as, the set up was SLOW. Simply at least 4-5 mins. Yet, it did work. If not try to uninstall it, or merely wait on a fix.