I would suggest to make sure you follow the instructions provided here to map your custom domain. <https://cloud.google.com/appengine/docs/standard/python/mapping-custom-domains>
If the issue persists, it is best to post your question on Stackoverflow <https://stackoverflow.com/> with the right tag and additional information, and experienced community members are within reach to help. Please note that Google Groups is reserved for general product discussions and is not for technical support. -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/google-appengine/88489678-ba9a-442f-91d6-5da9fad1500e%40googlegroups.com.
