Get string from Server.UrlEncode as uppercase

This will uppercase all escaped characters in your string.

string url = "http://whatever.com/something";
string lower = Server.UrlEncode(url);
Regex reg = new Regex(@"%[a-f0-9]{2}");
string upper = reg.Replace(lower, m => m.Value.ToUpperInvariant());

Uri.EscapeDataString("http://")

This code return

http%3A%2F%2F