Error in Ionic App

Hello,
I have an Ionic app which is working flawless in ionic serve --lab but when i build that app and install apk file in phone then it gives this error- “GET https://auth.firebase.com/v2/myexp/users?email=assffghggd%40gmail.com&password=65567&_method=POST&v=js-2.0.6&transport=json&suppress_status_codes=true 404 (Not Found)” and warning-" Passing in credentials to $createUser() as individual arguments has been deprecated in favor of a single credentials argument. See the AngularFire API reference for details." which i have inspected in chrome://inspect.
plz help