Dictionary<string, string> user = new Dictionary<string, string>();

                user.Add("__VIEWSTATE", __VIEWSTATE);

                user.Add("__VIEWSTATEGENERATOR", __VIEWSTATEGENERATOR);

                user.Add("__EVENTVALIDATION", __EVENTVALIDATION);

                var multiContent = new MultipartFormDataContent();

                foreach (var kvp in user)

                {

                    multiContent.Add(new StringContent(kvp.Value), kvp.Key);

                }

                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("multipart/form-data"));

                client.DefaultRequestHeaders.Clear();

                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/x-www-form-urlencoded"));

                HttpResponseMessage response = client.PostAsync("/ReservationList.aspx?st=0", multiContent).Result;

                string result = response.Content.ReadAsStringAsync().Result;

at System.UriHelper.EscapeString(String input, Int32 start, Int32 end, Char[] dest, Int32& destPos, Boolean isUriString, Char force1, Char force2, Char rsvd) at System.Uri.EscapeDataString(String stringToEscape) at System.Net.Http.FormUrlEncodedContent.Encode(String data) at System.Net.Http.FormUrlEncodedContent.GetContentByteArray(IEnumerable`1 nameValueCollection) at System.Net.Http.FormUrlEncodedContent..ctor(IEnumerable`1 nameValueCollection) at RmosAcentex.Models.sayfadiger() in C:\Users\RAMBO\source\repos\RmosAcentex\RmosAcentex\Models\Api.cs:line 127