I have been having the same error since 4PM EDT yesterday, after all the Google updates. Like others, it appears to be with Google+. Shut off all your notifications in Google+, sign out, then sign back in, and re-enable Notifications, Instant Upload, Messenger, or Hangouts, one at a time to see which one is causing the major problem. So far, I have notifications & Instant upload enabled and no further problems!
Same thing happened this morning. It started just after updating the new G+ apps. I thought it was due to my fiddling with 2-way authentication, but nope, that wasn't it. Tried reset/reinstall everything. Also tried changing new password. Same thing happened again after installing with the new G+. That must be it. See if can wait it out for another bug fix update.