Security News > 2020 > December > Google explains the cause of the recent YouTube, Gmail outage
As a direct result, users weren't able to access Gmail, YouTube, Google Drive, Google Maps, Google Calendar, and several other Google services for almost an hour on Monday, December 14th. During the outage, users could not send emails via Gmail mobile apps or receive email via POP3 for desktop clients, while YouTube visitors were seeing error messages stating that "There was a problem with the server - Tap to retry."
"The majority of authenticated services experienced similar control plane impact: elevated error rates across all Google Cloud Platform and Google Workspace APIs and Consoles."
The Google User ID Service that was at the root of the major Google outage from Monday stores unique identifiers for all Google accounts and it manages authentication credentials for both OAuth tokens and cookies.
Since the User ID Service service will reject requests when detecting outdated data for security reasons, all customer-facing Google services requiring Google OAuth access became unavailable right after the service started experiencing issues and began issuing outdated identifiers.
"A configuration change during this migration shifted the formatting behavior of a service option so that it incorrectly provided an invalid domain name, instead of the intended 'gmail.com' domain name, to the Google SMTP inbound service," Google said.