+            else:
+                CHALLENGES = {
+                    'LOGIN_CHALLENGE': "This device isn't recognized. For your security, Google wants to make sure it's really you.",
+                    'USERNAME_RECOVERY': 'Please provide additional information to aid in the recovery process.',
+                    'REAUTH': "There is something unusual about your activity. For your security, Google wants to make sure it's really you.",
+                }
+                challenge = CHALLENGES.get(
+                    challenge_str,
+                    '%s returned error %s.' % (self.IE_NAME, challenge_str))
+                warn('%s\nGo to https://accounts.google.com/, login and solve a challenge.' % challenge)
+                return False