Our HP ALM version is 12.20 From the reference link https://www.aneejian.com/2017/03/hp-alm-rest-api-authentication.html I am able to authenticate user but when try for test set update or get project information from QC I am getting HTTP 404 error.
I tried even by creating the cookie but still facing the same HTTP 404.
After adding cookie to site-session object able to maintain session.
string LWSSOCookie = AuthCookies.Substring(AuthCookies.IndexOf("LWSSO_COOKIE_KEY=") + 17);
LWSSOCookie = LWSSOCookie.Substring(0, LWSSOCookie.IndexOf(";"));
createSessionRequest.CookieContainer.Add(new Cookie("LWSSO_COOKIE_KEY", LWSSOCookie){ Domain = target.Host });
Finally need to add the "createSessionRequest" CookieContainer to ALM get service.