How did you configure the custom domain and the SSL certificates, exactly? A step-by-step description would help a lot. Have you followed any document?
After you set up your custom domain and update the DNS records, a managed SSL certificate is automatically provided within a few minutes. Have you verified that the SSL certificate has been actually provisioned? You can do that by running: gcloud beta app domain-mappings list You should see a list of your domains, subdomains, and all their corresponding certificates, for example: ID SSL_CERTIFICATE_ID example.com 123456 www.example.com 234567 You can gather more relevant detail from the "Securing Custom Domains with SSL" documentation page <https://cloud.google.com/appengine/docs/standard/python/securing-custom-domains-with-ssl> . Any other piece of information you deem relevant might prove of great help. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-appengine+unsubscr...@googlegroups.com. To post to this group, send email to email@example.com. Visit this group at https://groups.google.com/group/google-appengine. To view this discussion on the web visit https://groups.google.com/d/msgid/google-appengine/3571035b-a58c-42ad-9294-924c63251431%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.