Yeah, a lot of people do, apparently. However, if you’re a client (not the server administrator) and you’re pretty much positive that the server isn’t configured incorrectly, you don’t have a proxy server on your side, it’s not supposed to be plain HTTP….you might still be confused after you read all that stuff.
I was using a cURL command with –anyauth. That’s supposed to work by negotiating the most secure authorization possible with the server, but apparently it doesn’t always work, and it can cause this error. When I changed –anyauth to -3 (short for ‘use SSL3′), magically the problem went away.
Your mileage may vary.