Status Code: 404; Not Found 

app.UseExceptionHandler("/errors/500");
app.UseStatusCodePagesWithReExecute("/errors/{0}");

public class ErrorsController : Controller
{
 [Route("errors/{statusCode}")]
 public IActionResult CustomError(int statusCode)
 {
  if(statusCode == 404)
  {
   return View("~/Views/Errors/404.cshtml");
  }
  return View("~/Views/Errors/500.cshtml");
 }  
}

System.DllNotFoundException: Unable to load DLL 'System.Security.Cryptography.Native.Apple': The specified module could not be found.
 (Exception from HRESULT: 0x8007007E)

app.UseExceptionHandler(errorApp =>
{
 errorApp.Run(async context =>
 {
  context.Response.StatusCode = 500;
  if (context.Request.Headers["X-Requested-With"] != "XMLHttpRequest")
  {
   context.Response.ContentType = "text/html";
   await context.Response.SendFileAsync($@"{env.WebRootPath}/errors/500.html");
  }
 });
});
app.UseStatusCodePagesWithReExecute("/errors/{0}");

public class ErrorsController : Controller
{
 private IHostingEnvironment _env;

 public ErrorsController(IHostingEnvironment env)
 {
  _env = env;
 }

 [Route("errors/{statusCode}")]
 public IActionResult CustomError(int statusCode)
 {
  var filePath = $"{_env.WebRootPath}/errors/{(statusCode == 404?404:500)}.html";
  return new PhysicalFileResult(filePath, new MediaTypeHeaderValue("text/html"));
 }  
}