Reports of the glitch flooded the Twitter microblogging service on Thursday, with users posting comments highlighting and griping about the situation.
A message appearing at the top of the Gmail product for some people stated that Gmail "is temporarily unable to access your contacts. You may experience issues while this persists."
A Google representative was not immediately available to comment.
Earlier this month, most Google email users were unable to access its service for more than an hour. Google said the outage was due to some of its routers becoming overloaded during a routine upgrade. [ID:nN01486322]
Google called that outage a "big deal" on its official blog.
On Tuesday, Google's news website experienced a nearly two-hour outage. (Reporting by Alexei Oreskovic, editing by Leslie Gevirtz)