Firebase-ios-sdk: Firebase Auth with Microsoft (Azure AD) - Login not possible - "Unable to process request due to missing initial state"

Created on 13 Dec 2020 · 5Comments · Source: firebase/firebase-ios-sdk

[REQUIRED] Step 1: Describe your environment

Xcode version: XCode 12.2 (12B45b)
Firebase SDK version: 7.3.0
Installation method: CocoaPods
Firebase Component: Auth

[REQUIRED] Step 2: Describe the problem

Steps to reproduce:

When logging in to Firebase with Microsofts Azure AD as an authentication service by using provider.getCredentialWith(_: nil) I am able to open the Microsoft login page.
After entering the correct email + password then the following error appears inside the In-App-Browser:
"Unable to process request due to missing initial state. This may happen if browser sessionStorage is inaccessible or accidentally cleared."

The problem appears no matter if I set Chrome or Safari as a standard browser in iOS settings.
It happens on real devices (iPhone and iPad, iOS 14.2/14.3 and others), but not every user is affected. Most users can login without any problems.
I can't determine in what kind of circumstances the problem occurs, but on a device where the problem occurs, it is always reproducable.

What did work for me as a workaround:
In my completion handler of provider.getCredentialWith(_: nil) I call the same function with a delay of 1second again if an error was thrown. On the second run it always succeeds and gives me the credentials back.

Relevant Code:

                        provider.getCredentialWith(_: nil){credential, error in
                            if error != nil {
                                self.errorText = "Error"
                                return
                            }
                            if let credential = credential {
                                firebaseSignIn(credential: credential)
                            }
                        }

auth

Source