Error logging and handling in asp.net core mvc - asp.net-core

Question

Let's say you made a bug in a code (like this for example 415 Unsupported Media Type asp.net core ). And get 415 error from a web request. How do we find more information about the error? How can we log it?
Seems that .UseExceptionHandler() In Startup.cs does not catch it.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILoggerFactory loggerFactory)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
// app.UseExceptionHandler("/Home/Error");
}
else
{
app.UseExceptionHandler("/Home/Error");
// The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
app.UseHsts();
}
app.UseStatusCodePages(async context =>
{
context.HttpContext.Response.ContentType = "text/plain";
var statusCodeData = context.HttpContext.Features.Get<IStatusCodePagesFeature>();
await context.HttpContext.Response.WriteAsync(
"Status code page, status code: " +
context.HttpContext.Response.StatusCode);
});
// app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllerRoute(
name: "default",
pattern: "{controller=Home}/{action=Index}/{id?}");
});
}

Answer 1

Try with Middleware. Create new class for Middleware:
public class ErrorLoggingMiddleware
{
private readonly RequestDelegate _next;
public ErrorLoggingMiddleware(RequestDelegate next)
{
_next = next;
}
public async Task Invoke(HttpContext context)
{
try
{
await _next(context);
}
catch (Exception exception)
{
// Handle exception
await HandleExceptionAsync(context, exception, HttpStatusCode.InternalServerError);
}
}
private Task HandleExceptionAsync(HttpContext context, Exception exception, HttpStatusCode statusCode)
{
context.Response.StatusCode = (int)statusCode;
// TO DO: Log exceptions : Azure AppInsights or File
var message = "The requested resource was not found";
var response = new
{
ErrorDescription = $"{(int)statusCode} - {message}",
ErrorCode = message
};
string responseStringContent;
context.Response.ContentType = Application.Json;
responseStringContent =
JsonSerializer.Serialize(response, new JsonSerializerOptions() { PropertyNamingPolicy = JsonNamingPolicy.CamelCase });
return context.Response.WriteAsync(responseStringContent);
}
}
Then configure this class in Startup:
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory fac)
{
...
app.UseMiddleware<ErrorLoggingMiddleware>();
...
}
Please find more details at:
https://blog.elmah.io/error-logging-middleware-in-aspnetcore/