Sorry, something didn’t work correctly.
If we knew exactly what the problem was, we would tell you instead of giving you this useless error message. Actually, if we knew, we would most likely have fixed it already.
Rest assured. As you read this, alarm bells are ringing at the Googleplex, signifying something has gone horribly wrong in this quadrant. A report will soon be in the hands of our engineering team, detailing the bad thing that happened here. This team will work without rest to address the problem you have brought to their attention.
If, after a decent interval (about 24 hours), you encounter this problem again, please email us at email@example.com. The more specifics you include, the better (e.g., what kind of computer and browser you were using, what page you looked at last, what you clicked on, etc.). Sometimes, even our engineers need a little help.
Thanks for using Google.