Fatal error: Unexpectedly found nil while unwrapping an Optional value . Problem occurs when i add in firebase . Swift 4 [duplicate]

This question already has an answer here: What does “fatal error: unexpectedly found nil while unwrapping an Optional value” mean? 11 answers I have an error when adding objects in FirebaseDatabase. I have an error which occurs in self.database.child(“user_profiles”).child(self.user!.uid).child(“username”).setValue(self.UsernameField.text!) Unexpectedly found nil while unwrapping an Optional value. I am writing in Swift 4. @IBOutlet weak…

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