Tag: Exception Handling

Categories
ASP.NET Core

Developer Exception Page in ASP.NET Core

Developer-Exception-Page-in-ASP.NET-Core

The developer exception page is a one of the error handling processes in ASP.Net Core. It will give you complete details about the exception.

To enable the Developer exception page app.UseDeveloperExceptionPage(); should be added in Configure method in Startup.cs file. The  app.UseDeveloperExceptionPage(); must appear before the middleware  which needs to handle the exception.

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    if (env.IsDevelopment())
    {
    app.UseDeveloperExceptionPage();
    }
}

The Developer Exception  Page will have the following Information

  • Stack
  • Query
  • Cookies
  • Headers
  • Routing

Let’s look at a small example of how the exception is displayed in the browser without app.UseDeveloperExceptionPage() and app.UseDeveloperExceptionPage(). I  have commanded the exception handling process from the Configure method in Startup.cs 

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    //if (env.IsDevelopment())
    //{
    //    app.UseDeveloperExceptionPage();
    //}
    //else
    //{
    //    app.UseExceptionHandler(“/Error”);
    //    app.UseHsts();
    //}

    app.UseHttpsRedirection();
    app.UseStaticFiles();
    app.UseRouting();
    app.UseAuthorization();
    app.UseEndpoints(endpoints =>
    {
    endpoints.MapRazorPages();
    });
}

The following is a screenshot of the exception. It does not clearly show what the exception is.

It Just says “This page isn’t working, localhost is currently unable to handle this request. HTTP ERROR 500”

Developer Exception

In the below code I have uncommanded the exception handling process.

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    if (env.IsDevelopment())
    {
    app.UseDeveloperExceptionPage();
    }
    else
    {
    app.UseExceptionHandler(“/Error”);
    app.UseHsts();
    }

    app.UseHttpsRedirection();
    app.UseStaticFiles();
    app.UseRouting();
    app.UseAuthorization();
    app.UseEndpoints(endpoints =>
    {
     endpoints.MapRazorPages();
    });
}

The following is a screenshot of the Developer Exception page. It clearly states what the exception is. It also shows on which page and line it is occurring.

pasted image

Note:

Enable the Developer Exception Page exception in the developer environment to avoid sharing the exception details in public.

If you have any questions, please leave a comment below.

Categories
ASP.NET Core

Turn on CircuitOption.DetailedError in Blazor

Turn on CircuitOption.DetailedError in Blazor

This article is going to explain how to enable CircuitOption.DetailedError in the development environment.

Let us look at a small example. The following is the Blazor component code. It contains both HTML and @code block. GetArray() method is defined in the @code module. In it, the array is initialized with four elements.  Finally, arr [5] is assigned to the result variable so that it triggers an index outside the range exception.

@page “/”

<h4>Turn on CircuitOption.DetailedError</h4>

<button @onclick=”GetArray”>Trigger the Exception</button>

@code
{
    void GetArray()
    {
        int[] arr = new int[] { 1, 2, 3, 4 };
        int result = arr[5];
    }
}

The following screenshot illustrates how the exception is displayed in the browser. It states, Error: There was an unhandled exception on the current circuit, so this circuit will be terminated. For more details turn on detailed exceptions in ‘CircuitOptions.DetailedErrors’.

CircuitOption.DetailedError

Let us see how to enable the CircuitOption.DetailedError.

In the Startup.cs file, IWebHostEnvironment  is initialized to provide web hosting environment information. Added  IWebHostEnvironment  in Startup constructor. Finally, AddCircuitOptions has been added in the ConfigureServices method, which helps to configure circuits.

In this code _Env.Is Development () is checked to confirm if it is a development environment or not. If it is a development environment, then only it will display the detail error.

private readonly IWebHostEnvironment _env;

public Startup(IConfiguration configuration, IWebHostEnvironment env)
{
    Configuration = configuration;
    _env = env;
}

public void ConfigureServices(IServiceCollection services)
{
    services.AddRazorPages();

    services.AddServerSideBlazor().AddCircuitOptions(options => {
       if (_env.IsDevelopment())
      {
        options.DetailedErrors = true;
      }
    });

    services.AddSingleton<WeatherForecastService>();
}

The following screenshot illustrates how the browser displays the error after enabling a detailed error. It clearly states what the error is and shows which file it is and which line number it occurs.

CircuitOption.DetailedError in Blazor

The blog explains how to enable CircuitOption.DetailedError in the development environment.

If you have any questions, please leave a comment.