Swift Xcode Firebase Error 'nw_connection_receive_internal_block_invoke'

Question

Using Swift, Firebase, and Xcode 11, I am starting to create a social media app. While creating the sign in page's image-icon-upload thingy, after I run my code, insert the email/username/password, and enter the signIn/signUp button, I get this error:

nw_connection_receive_internal_block_invoke [C1] Receive reply failed with error "Operation canceled"

Here is my view controller code inside my signIn/signUp button's image part of the @IBAction:

//Image Upload
var downloadURL: URL!

if let imageData = self.selectedImage.jpegData(compressionQuality: 0.2) {
       let metaData = StorageMetadata()
       Storage.storage().reference().putData(imageData, metadata: metaData) { (metadata, error) in
            guard let metadata = metadata else {
                 // Uh-oh, an error occurred!
                 return
            }
            // Metadata contains file metadata such as size, content-type.
            let size = metadata.size

            self.storageRef.downloadURL { (url, error) in
                 downloadURL = url
            }
            Database.database().reference().child("user").child((user?.user.uid)!).setValue([
                 "username": self.usernameField.text,
                 "userImg": downloadURL
            ])
       }
}

Any ideas?