When the title of this entry looks familiar (You must have been directed here by a search engine. :)) my guess is that you have been using libCurl and somehow got it to report this error message.

In my case it happened because I was doing a download, an upload, and a download again. The last download failed with the above error. Searching for an answer got me to think it was the server side not responding well to a request. This wasn’t the case at all.

The reason was simple. I was re-using a transfer class and not resetting all the libCurl options to their defaults, so some of the upload options leaked to the last download call.