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

Categories : ASP.NET Core

Author : Golda G Date : Mar 21, 2022

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.

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