Proxy authentication required (http error 407) with WinHttpRequest and proxy with integrated Windows authentication and https

Question

I'm trying to access an external website from my company network using WinHttpRequest from VBA. The company has a proxy server that requires integrated Windows authentication.

The following code works if I try to access a URL with plain http, but I get http status code 407 - proxy authentication required if I try to access a URL with https.

What do I need to do to make the code work with https?

Sub a()
    Dim w As New WinHttp.WinHttpRequest

    'set proxy        
    w.SetProxy 2, "myproxy:8080"
    'use integrated windows authentication
    w.SetAutoLogonPolicy AutoLogonPolicy_Always
    w.Option(WinHttpRequestOption_EnableRedirects) = True
    w.Open "GET", "https://..."
    w.Send
    Debug.Print w.Status ' Status = 407
    Debug.Print w.Option(WinHttpRequestOption_URL)
End Sub

Answer 1

Try, please insert (between Open and Send) a line for setting credentials and another one for ignoring (all) SSL errors. Try something lile that:

Sub AccessSiteThroughProxy()
    Dim w As New WinHttp.WinHttpRequest

    'set proxy
    w.setProxy 2, "myproxy:8080"
    'use integrated windows authentication
    w.SetAutoLogonPolicy AutoLogonPolicy_Always
    w.Option(WinHttpRequestOption_EnableRedirects) = True
    w.Open "GET", "https://..."

    'try inserting a line to set credentials:________________________________________
     w.SetCredentials UserName, Password, HTTPREQUEST_SETCREDENTIALS_FOR_SERVER ' try Const HTTPREQUEST_SETCREDENTIALS_FOR_SERVER = 0
     'in order to ignore SSL erors, try:
     w.Option(WinHttpRequestOption_SslErrorIgnoreFlags) = &H3300
    '_________________________________________________________________________________

    w.send
    Debug.Print w.Status ' Status = 407
    Debug.Print w.Option(WinHttpRequestOption_URL)
End Sub