ActionController::InvalidAuthenticityToken Rails 5 / Devise / Audited / PaperTrail Gem
Answer : As it turns out, Devise documentation is quite revealing with regard to this error: For Rails 5 , note that protect_from_forgery is no longer prepended to the before_action chain, so if you have set authenticate_user before protect_from_forgery , your request will result in " Can't verify CSRF token authenticity. " To resolve this, either change the order in which you call them, or use protect_from_forgery prepend: true . The fix was to change code in my application controller from this: protect_from_forgery with: :exception To this: protect_from_forgery prepend: true This issue did not manifest itself until I attempted adding Audited or Paper Trail gems.