ASP.NET Core + ApplicationInsights Logging Errors as Trace

If you want to log the error as Exception in app insights, this line of code _logger.LogError("Test", new Exception("Test")); should be changed.

Change it to _logger.LogError(new Exception(), "test");, which means the new Exception() should be the first paramter.

And you can add application insights SDK by right click your project -> add -> Application Insights Telemetry, which is very useful doing some thing automatically(ie. adding .UseApplicationInsights() in Programs.cs):

I also post my test steps:

1.Adding application insights SDK as mentioned above

2.Add loggerFactory.AddApplicationInsights(app.ApplicationServices,LogLevel.Information); in Startup.cs -> Configure() method, code as below:

            public void Configure(IApplicationBuilder app, IHostingEnvironment env,ILoggerFactory loggerFactory)
            {
                if (env.IsDevelopment())
                {
                    app.UseDeveloperExceptionPage();
                }
                else
                {
                    app.UseExceptionHandler("/Error");
                    app.UseHsts();
                }

                app.UseHttpsRedirection();
                app.UseStaticFiles();
                app.UseCookiePolicy();

                app.UseMvc();

                //Add this line of code
                loggerFactory.AddApplicationInsights(app.ApplicationServices,LogLevel.Information);
            }

3.Then in somewhere you wanna log error:

        public class AboutModel : PageModel
        {
            private ILogger _logger;

            public AboutModel(ILogger<AboutModel> logger)
            {
                _logger = logger;
            }

            public string Message { get; set; }

            public void OnGet()
            {
                _logger.LogInformation("it is just a test herexxxx");

               //Only this format can log as exception
                _logger.LogError(new Exception(), "it is a new Exceptionxxxx");

               //it will log as trace
                _logger.LogError("error logs xxx");
                Message = "Your application description page.";
            }
        }

4.Test result as below:

Since Microsoft.ApplicationInsights.AspNet v2.7 the question and the accepted answer are outdated, as calling AddApplicationInsights on ILoggerFactory is now obsolete.

Please refer to the official docs.

The gist from the docs:

1. ApplicationInsightsLoggerProvider is enabled by default.
2. Captured log types can be configured in appsettings.json (or programmatically if you really need it)

    "Logging": {
        "LogLevel": {
            "Default": "Warning"
        },
        "ApplicationInsights": {
            "LogLevel": {
                "Default": "Error"
            }
        }
    }