#flyone won't proceed adding a document to a profile without DOB... for which it doesn't provide a field -- the (otherwise optional) field is buried in the other pages of the profile. not very obvious
Logging in to @stackoverflow .. on failed login sites shouldn't tell you which piece of login info was incorrect. It makes it harder for malicious user to know what need to keep trying to "guess". Probably a stretch to call this a bug, could even been a compromise for end user friendliness (considering SO is no banking app), but strictly speaking may not be the best practice.
not that lucky, I guess