502 usually results from an intermediate gateway/proxy unable to understand server’s response.

If however, you don't expect a gateway or proxy to sit between your client and server, this error may result from a misconfigured proxy settings on your client box.

To view, proxy settings, run the following on your client box:

    netsh winhttp show proxy

The problem should go away once you reset your client side proxy configuraiton

   netsh winhttp reset proxy