Facebook login is broken. How to fix?

Question

Ruby on Rails

Everything worked before and now it gives an error " You cannot log in with your Facebook account, bad credentials. " I looked at the WebRick log: " Error validating verification code. Please make sure your redirect_uri is identical to the one you used in the OAuth dialog request ". Found this article, there they did it. Suggested to add "/" to the end of redirect_uri does not help me, another error appears: rails 4.2
devise 3.5.1
omniauth-facebook 2.0
env = development
host = 127.0.0.1:3000