Asp.Net Core 6 Web API - How to return only 400 Bad requests

I will check and let you know, thank you.

Hi @Zhi Lv - MSFT

I am somehow still getting 500 Internal Server error. Here is the code;

private static async Task HandleExceptionAsync(HttpContext context, Exception exception)
        {
            try
            {
                _logger.LogError("Web API Exception Handler Error: " + exception);
                await using var sqlConnection =
                    new SqlConnection(_configuration.GetSection("ConnectionStrings:OyunPalasDbContext").Value);
                await using var cmd =
                    new SqlCommand(
                        "INSERT INTO [dbo].[APIError] ([Message],[RequestMethod],[RequestUri],[TimeUtc]) VALUES (@Message, @RequestMethod, @RequestUri, @TimeUtc)",
                        sqlConnection);
                sqlConnection.Open();

                cmd.Parameters.AddWithValue("@Message", exception.Message);
                cmd.Parameters.AddWithValue("@TimeUtc", DateTime.Now);
                cmd.Parameters.AddWithValue("@RequestUri", context.Request.Path.ToString());
                cmd.Parameters.AddWithValue("@RequestMethod", context.Request.Method.ToString());

                if (exception.InnerException != null)
                {
                    cmd.Parameters.AddWithValue("@Message", exception.Message + " " + exception.InnerException);
                    _logger.LogError("Web API Exception Handler Inner Error: " + exception.InnerException);
                }

                cmd.ExecuteNonQuery();
            }
            catch (Exception e)
            {
                _logger.LogError("Web API Exception Handler insert error: " + e.Message);
            }

            if (exception is BadHttpRequestException)
            {
                //400 exception.
                context.Response.ContentType = "application/json";
                context.Response.StatusCode = (int)HttpStatusCode.BadRequest;
                await context.Response.WriteAsync(new ErrorDetails()
                {
                    StatusCode = context.Response.StatusCode,
                    Message = exception.Message
                }.ToString());
            }
            else
            {
                //return 500 error
                context.Response.ContentType = "application/json";
                context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
                await context.Response.WriteAsync(new ErrorDetails()
                {
                    StatusCode = context.Response.StatusCode,
                    Message = "Internal Server Error."
                }.ToString());
            }
            
        }

Even though it enters the correct if branch (Bad request), still returns 500? How?

Even though it enters the correct if branch (Bad request), still returns 500? How?

Is there any other exception handler method? Whether the returned 500 error is the custom error (ErrorDetails) or not? I checked the code again, it still works well on my side, can you create a minimal, complete sample to reproduce the problem?

There is a request-response middleware that logs requests and responses. I got 500 in the line** Call the next middleware in the pipeline**. I couldn't understand why.

public class RequestResponseMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly IConfiguration _configuration;
        private readonly bool _isRequestResponseLoggingEnabled;

        public RequestResponseMiddleware(RequestDelegate next, IConfiguration configuration)
        {
            _next = next;
            _configuration = configuration;
            _isRequestResponseLoggingEnabled = configuration.GetValue<bool>("EnableRequestResponseLogging", true);
        }

        public async Task InvokeAsync(HttpContext httpContext)
        {
            // Middleware is enabled only when the EnableRequestResponseLogging config value is set.
            if (_isRequestResponseLoggingEnabled)
            {
                await using var sqlConnection =
                    new SqlConnection(_configuration.GetSection("ConnectionStrings:OyunPalasDbContext").Value);

                await using var cmd =
                    new SqlCommand(
                        "INSERT INTO [dbo].[API_Log] ([Host],[Headers],[StatusCode],[TimeUtc],[RequestBody],[RequestedMethod],[UserHostAddress],[Useragent],[AbsoluteUri],[RequestType]) VALUES (@Host,@Headers,@StatusCode,getdate(),@RequestBody,@RequestedMethod,@UserHostAddress,@Useragent,@AbsoluteUri,@RequestType)",
                        sqlConnection);
                sqlConnection.Open();

                cmd.Parameters.AddWithValue("@Host", httpContext.Request.Host.ToString());
                cmd.Parameters.AddWithValue("@StatusCode", "");
                cmd.Parameters.AddWithValue("@Headers", FormatHeaders(httpContext.Request.Headers));
                cmd.Parameters.AddWithValue("@RequestBody", await ReadBodyFromRequest(httpContext.Request));
                cmd.Parameters.AddWithValue("@RequestedMethod", httpContext.Request.Method);
                cmd.Parameters.AddWithValue("@UserHostAddress", httpContext.Request.Host.ToString());
                cmd.Parameters.AddWithValue("@Useragent", httpContext.Request.Headers["User-Agent"].ToString());
                cmd.Parameters.AddWithValue("@AbsoluteUri", httpContext.Request.Path.ToString());
                cmd.Parameters.AddWithValue("@RequestType", "Request");

                cmd.ExecuteNonQuery();

                var originalResponseBody = httpContext.Response.Body;
                using var newResponseBody = new MemoryStream();
                httpContext.Response.Body = newResponseBody;

                // Call the next middleware in the pipeline
				//After calling this I got 500 Internal Server Error
                await _next(httpContext);

                newResponseBody.Seek(0, SeekOrigin.Begin);
                var responseBodyText = await new StreamReader(httpContext.Response.Body).ReadToEndAsync();

                await using var sqlConnectionResponse =
                    new SqlConnection(_configuration.GetSection("ConnectionStrings:OyunPalasDbContext").Value);

                await using var cmdResponse =
                    new SqlCommand(
                        "INSERT INTO [dbo].[API_Log] ([Host],[Headers],[StatusCode],[TimeUtc],[RequestBody],[RequestedMethod],[UserHostAddress],[Useragent],[AbsoluteUri],[RequestType]) VALUES (@Host,@Headers,@StatusCode,getdate(),@RequestBody,@RequestedMethod,@UserHostAddress,@Useragent,@AbsoluteUri,@RequestType)",
                        sqlConnectionResponse);
                sqlConnectionResponse.Open();

                cmdResponse.Parameters.AddWithValue("@Host", httpContext.Request.Host.ToString());
                cmdResponse.Parameters.AddWithValue("@Headers", FormatHeaders(httpContext.Response.Headers));
                cmdResponse.Parameters.AddWithValue("@StatusCode", httpContext.Response.StatusCode.ToString());
                cmdResponse.Parameters.AddWithValue("@RequestBody", responseBodyText);
                cmdResponse.Parameters.AddWithValue("@RequestedMethod", httpContext.Request.Method);
                cmdResponse.Parameters.AddWithValue("@UserHostAddress", httpContext.Request.Host.ToString());
                cmdResponse.Parameters.AddWithValue("@Useragent", "");
                cmdResponse.Parameters.AddWithValue("@AbsoluteUri", "");
                cmdResponse.Parameters.AddWithValue("@RequestType", "Response");

                cmdResponse.ExecuteNonQuery();

                newResponseBody.Seek(0, SeekOrigin.Begin);
                await newResponseBody.CopyToAsync(originalResponseBody);
            }
            else
            {
                await _next(httpContext);
            }
        }

        private static async Task<string> ReadBodyFromRequest(HttpRequest request)
        {
            // Ensure the request's body can be read multiple times (for the next middlewares in the pipeline).
            request.EnableBuffering();

            using var streamReader = new StreamReader(request.Body, leaveOpen: true);
            var requestBody = await streamReader.ReadToEndAsync();

            // Reset the request's body stream position for next middleware in the pipeline.
            request.Body.Position = 0;
            return requestBody;
        }

        private static string FormatHeaders(IHeaderDictionary headers) => string.Join(", ", headers.Select(kvp => $"{{{kvp.Key}: {string.Join(", ", kvp.Value)}}}"));
    }

I got 500 in the line** Call the next middleware in the pipeline**. I couldn't understand why.

You can set break point in the next middleware and check why it throw 500 error. Besides, since there have multiple custom middleware, you'd better to check the middleware order.