There are quite a number of reasons why a timeout may be returned from App Engine. It may be a result of some network issues while trying to reach google apis. To determine specifically the root cause of the issue experienced on your application, I recommend that you open an issue using the issue tracker link[1][2]. This way a GCP Support engineer would be able to work closely with you, reviewing your application configuration and determine exactly what may be the cause of the timeout.
[1]https://cloud.google.com/support/docs/issue-trackers#trackers-list [2]https://issuetracker.google.com/issues/new?component=187191&template=0 -- 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/86612f76-9e55-496a-aa30-9c8a0923b219%40googlegroups.com.
