Global Error Handling in ASP.NET Core MVC

Question

I tried to implement a global error handler on my Asp.net core mvc web page. For that I created an error handler middleware like described on this blog post.

    public class ErrorHandlerMiddleware
{
    private readonly RequestDelegate _next;

    public ErrorHandlerMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task Invoke(HttpContext context)
    {
        try
        {
            await _next(context);
        }
        catch (Exception error)
        {
            var response = context.Response;
            response.ContentType = "application/json";

            switch (error)
            {
                case KeyNotFoundException e:
                    // not found error
                    response.StatusCode = (int)HttpStatusCode.NotFound;
                    break;
                default:
                    // unhandled error
                    response.StatusCode = (int)HttpStatusCode.InternalServerError;
                    break;
            }

            var result = JsonSerializer.Serialize(new { message = error?.Message });
            await response.WriteAsync(result);
            context.Request.Path = $"/error/{response.StatusCode}"; // <----does not work!
        }
    }
}

The middleware works as expected and catches the errors. As a result i get a white page with the error message. But i am not able to display a custom error page. I tried it with the following line of code. But this does not work.

context.Request.Path = $"/error/{response.StatusCode}";

Any ideas how I can achive my goal?

Thanks in advance

I think you want the response to redirect to $"/error/{response.StatusCode}" — phuzi
– phuzi, Commented Nov 30, 2021 at 15:53
Exactly, but how can I do that? context.Response has no path attribut. — Pilouni
– Pilouni, Commented Nov 30, 2021 at 15:56
Try context.Response.Redirect($"/error/{response.StatusCode}") — phuzi
– phuzi, Commented Nov 30, 2021 at 16:02
Thank you that worked. But I had to remove the line await response.WriteAsync(result); as well to get it running. — Pilouni
– Pilouni, Commented Dec 1, 2021 at 6:04
Yeah, there's no point writing to the response when you're redirecting the browser anyway. — phuzi
– phuzi, Commented Dec 1, 2021 at 8:46

phuzi · Accepted Answer · 2021-12-01 08:51:42Z

1

It seems that you wish to redirect the browser to an error page.

To do this you'll need to replace:

context.Request.Path = $"/error/{response.StatusCode}";

With

context.Reponse.Redirect($"/error/{response.StatusCode}");

Also, since you're sending a redirect, the response content needs to be empty, so remove the response.WriteAsync bit too.

var result = JsonSerializer.Serialize(new { message = error?.Message });
await response.WriteAsync(result);

answered Dec 1, 2021 at 8:51

phuzi

13.3k4 gold badges30 silver badges65 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

KOMODO Over a year ago

not reponse. Response

phuzi Over a year ago

@KOMODO Typo corrected :o)

Collectives™ on Stack Overflow

Global Error Handling in ASP.NET Core MVC

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related