using System.Net;
//...
var content = new WebClient { Encoding = Encoding.UTF8 }.DownloadString(url);

var doc = new HtmlDocument
                {
                    OptionCheckSyntax = true,
                    OptionFixNestedTags = true,
                    OptionAutoCloseOnEnd = true,
                    OptionDefaultStreamEncoding = Encoding.UTF8
                };
doc.LoadHtml(content);

[HandleError(View = "~/Views/SomeLocation/Index.cshtml")]