Recently, our web application that uses OAuth2.0 authentication to connect to Google Drive has encountered a problem. We already registered and verified our application (through Google Console),and has not encountered this error before until March 9, 2022.

The following error is displayed after the username has been inputted: https://accounts.google.com/signin/rejected?rrk=46

PROBLEM: "This browser or app may not secure"

Upon redirecting the user to Google OAuth screen, the user will be able to input their username. However, when the user tries to proceed to password screen, they are prompted with the error. On March 8, 2022 and previous dates, we were able to use the app without this error. However on March 9, 2022, the error suddenly appeared.

We also already checked the following Sign in with a supported browser - Computer - Google Account Help and made sure that:

1. JavaScript is turned on
2. This is not a security or network issue in our work network since we can access just fine using other browsers (Chrome, Edge).
3. We are using browser-based OAuth2.0

Our initial thought is that Google may have updated their policy or OAuth2.0 contents, but we have not seen any announcement about it. The application version we have used on the day the error occurred and the prior dates are the same.

This is the browser where the error occurs: Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/534.34 (KHTML, like Gecko) qtbrowser/0.1

Is this browser not supported by Google anymore?