Webapp token retrieval error

[Bj Lawson]

We have had FCM running in production since 2019 on a Web/iOS/Android multiplatform app. Starting at ~3pm Eastern Time on Thursday, 7/1, one client began reporting the following error when our initialization code attempts to retrieve the token:

An error occurred while retrieving token. FirebaseError: Messaging: A problem occured while subscribing the user to FCM: Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project. (messaging/token-subscribe-failed).

    at Se.<anonymous> (firebase-messaging.js:1)

    at firebase-messaging.js:1

    at Object.next (firebase-messaging.js:1)

    at n (firebase-messaging.js:1)

Initially we were unable to reproduce the error, but a couple hours later this error started occurring in our development environment.

Nothing has changed with our FCM code for quite some time; we are currently running:

https://www.gstatic.com/firebasejs/7.2.2/firebase-app.js

https://www.gstatic.com/firebasejs/7.2.2/firebase-messaging.js

Is anyone else experiencing any issues? Google Cloud is not showing any issues with authentication.

What's extremely odd is that at the moment, I am only seeing this issue in my development environment -- my login in the staging and production environment are not seeing any error message and are retrieving a token a submitting to the server successfully.

Any thoughts are greatly appreciated!