Google one-tap sign-in stopped working. Possibly related to FedCM changes?

Question

Google one-tap stopped working. Console shows: [GSI_LOGGER]: The given login_uri is not allowed for the given client ID. Login for this site has been up and running for years, including as recently as yesterday.

Not sure if it's related, but we received an email last month indicating that the site would be migrating to FedCM in April. The email also indicated that no issues were detected so we could expect it to be seamless.

We are seeing the login failures on both of the sites in the OAuth project.

I've now followed the migration doc, adding data-use_fedcm_for_prompt="true" to the g_id_onload block but no luck. The email indicated we could postpone the migration by setting that value to false but it still doesn't work.

Answer 1

Looking at the error message, it seems that you didn't correctly set up Authorized redirect URIs value in Google Cloud console. See data-login_url and step 5 on this page.

Thanks, Herman

Answer 2

Apparently the redirect_uri behavior changed. The configured "Redirect URIs" had to be updated to include the full path, e.g., https://myhost.com/login. Before this, the trailing /login wasn't required. Hope this helps.