Asp.Net Core MVC capture application exception details - exception

Question

After some research I could not find a way to capture application exceptions in asp.net core mvc with preserving default error page behaviour. There are actually two ways for custom handling application errors. First and simple way is to configure app.UseExceptionHandler("/Home/Error"); this in the Startup.cs file, but this way I'd lost the default DEVELOPMENT error page pretty view. Other solution to customize error handling in asp.net core mvc is to define exception handler inline, but that would cause default error page to override as well:
app.UseExceptionHandler(
options => {
options.Run(
async context =>
{
context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
context.Response.ContentType = "text/html";
var ex = context.Features.Get<IExceptionHandlerFeature>();
if (ex != null)
{
var err = $"<h1>Error: {ex.Error.Message}</h1>{ex.Error.StackTrace }";
await context.Response.WriteAsync(err).ConfigureAwait(false);
}
});
}
);
I need just to capture error details, without overriding the default behaviour (pretty default error page, et cetera). I don't need any custom exception handler, in fact I just need to grab exception. I'd like to do it at application level, so custom ExceptionHandlerAttribute that implements IExceptionFilter won't work. That solution would remove the default error page, also I need to catch middleware errors, not only controler exceptions. Following approach is not applicable:
public class CustomExceptionFilter : IExceptionFilter
{
public void OnException(ExceptionContext context)
{
HttpStatusCode status = HttpStatusCode.InternalServerError;
String message = String.Empty;
var exceptionType = context.Exception.GetType();
if (exceptionType == typeof(UnauthorizedAccessException))
{
message = "Unauthorized Access";
status = HttpStatusCode.Unauthorized;
}
else if (exceptionType == typeof(NotImplementedException))
{
message = "A server error occurred.";
status = HttpStatusCode.NotImplemented;
}
else if (exceptionType == typeof(MyAppException))
{
message = context.Exception.ToString();
status = HttpStatusCode.InternalServerError;
}
else
{
message = context.Exception.Message;
status = HttpStatusCode.NotFound;
}
HttpResponse response = context.HttpContext.Response;
response.StatusCode = (int)status;
response.ContentType = "application/json";
var err = message + " " + context.Exception.StackTrace;
response.WriteAsync(err);
}
}
That's the page, that I'd like to keep:

Answer 1

The solution is to use Elm for ASP.NET Core applications, the sample code is provided by Microsoft on their GitHub account: https://github.com/aspnet/Diagnostics, also there is reworked, stable version of the ASP.NET Core MVC logger, described in my article https://www.codeproject.com/Articles/1164750/Error-logging-in-ASP-NET-Core-MVC-Elmah-for-Net-Co. Happy coding!