Google photo authentication issue

Another user faced an app verification issue, but wasn’t able to rectify it.

I provided a workaround for that person, which you might want to try:

1. In the screen where you have set up your client id (on Google itself), add this to your list of Redirect URLs: https://developers.google.com/oauthplayground. After you have finished the entire authentication process you can delete this URL.
2. Go to the Google OAuth2 Playground.
3. On the right, under the configuration select the option to “Use your own OAuth credentials”. Provide your client ID and secret there.
4. On the left, under “Step 1 Select & authorize APIs” in the box next to “Authorize APIs”, put in https://www.googleapis.com/auth/photoslibrary.readonly https://www.googleapis.com/auth/photoslibrary.sharing https://picasaweb.google.com/data/, then click “Authorize APIs”.
5. You will go through the authentication screens, and finally, the section under “Step 2 Exchange authorization code for tokens” gets activated. You will see an “Authorization code” populated, and you can “Exchange Authorization code for tokens”
6. That will get you the “Refresh token” and the “Access token”. Copy the “Refresh token” and save it under Photonic → Settings → Google Photos → Google Photos settings → Refresh Token (for Back-end / Server-side Authentication).