System.ArgumentNullException: String reference not set to an instance of a String. Parameter name: s at System.Text.Encoding.GetBytes(String s) at RoutingCloudService.Helper.RemoveAccent(String txt) in C:\Users\Gebruiker\source\repos\Web.NodeMapp.Tools.Old\RoutingCloudService\Classes\Helper.cs:line 343 at RoutingCloudService.Helper.GenerateSlug(String phrase) in C:\Users\Gebruiker\source\repos\Web.NodeMapp.Tools.Old\RoutingCloudService\Classes\Helper.cs:line 330 at RoutingCloudService.Webservices.downloadGpx.ProcessRequest(HttpContext context) in C:\Users\Gebruiker\source\repos\Web.NodeMapp.Tools.Old\RoutingCloudService\Webservices\downloadGpx.ashx.cs:line 28