Google users have sporadically seen Google 502 (bad gateway) errors the last several years. The errors appear momentarily and then disappear. I’ve linked to a few postings about it according to date:
Google API users have seen the 502 errors much more frequently:
Nov 2005, and another
Feb 2006, and another
From my investigations, it looks like Nov 2005 is when the problems began. I have personally dealt with the problem ever since Mar 2006 when I integrated the Google API into Warrick. I had to add some logic to sleep for 15-20 seconds when encountering the error and then re-try.
In late May I started a new experiment which uses the Google API, and I’ve been monitoring it daily to see how many 502 errors I was receiving. From late May to June 6, I consistently received a 502 error for about 30% of my requests. On June 7, the number of 502s went down to zero. I have only received an occasional 502 out of hundreds of requests made daily.
Someone at Google finally got sick of the bad press and made some changes, and I’m thankful for it. :)