Implement Custom Error Pages

A set of tutorials for creating and implementating custom error pages in an Umbraco CMS project.

Umbraco is built on Microsoft's .NET Framework and uses ASP.NET. This provides different options when setting up custom error pages on your website.

Implementing custom error handling can make your site look more on-brand and minimize the impact that errors have on user experience. For example, a custom 404 page with helpful links or a search function can add extra value to your site.

In-code error page handling

In Umbraco, in-code error page handling refers to managing and displaying custom error pages directly through code. This method provides greater flexibility and control over how errors are handled and presented to users, especially within the context of an Umbraco site.

This article contains guides on how to create custom error pages for the most common scenarios:

• 404 Errors ("Page not found")

• 500 Errors ("Internal Server Error")

• Boot Failed Errors

Are you looking for a guide to create a custom maintenance page?

This has been moved to a separate article: Create a custom maintenance page.

404 Errors

A 404 error occurs when a requested page cannot be found, usually due to deleted content, a changed URL, or an invalid path. In Umbraco, you can create and configure custom 404 pages using content from the backoffice.

Create a 404 page in the backoffice

1. Go to the Settings section in the Umbraco backoffice.

2. Create a new Document Type with Template.

3. Name the Document Type ErrorPage404.

4. [Optional] Add any custom properties you want — though most 404 pages are static.

5. Click Save.

6. Go to the Templates folder.

7. Add your custom markup and design for the error page in the template. In this case, ErrorPage404.

8. Click Save.

Create a Container for Status Code Pages

1. Create a new Document Type.

2. Name it Statuscodes.

3. Go to the Structure Workspace view.

   • Enable Allow at root.

   • Add the ErrorPage404 Document Type as an Allowed child node types.

   • Click Choose.

4. Click Save.

Add the Content

1. Go to the Content section.

2. Create a new content node based on the Statuscodes Document Type and name it Statuscodes.

3. Click Save or Save and Publish.

4. Under it, create a child node using the ErrorPage404 Document Type.

5. Name it Page 404 Not Found or similar.

   • This will be the content shown when a 404 error occurs.

6. Click Save or Save and Publish.

Configure the Error Page in appsettings.json file

After publishing the 404 page, you’ll need to connect it in your configuration.

1. Go to the Info tab of your Page 404 Not Found content item in the Backoffice.

2. Copy the Id of the page (for example: 9c2b5196-30cd-4416-ae30-94ac2afb1011).

3. Go to your project's appsettings.json file.

4. Add the Error404Collection setting to Umbraco:CMS:Content, like shown below:

{
    "Umbraco": {
        "CMS": {
            "Content": {
                "Error404Collection": [
                    {
                        "Culture": "default",
                        "ContentKey": "9c2b5196-30cd-4416-ae30-94ac2afb1011"
                    }
                ]
            }
        }
    }
}

Replace the value for ContentKey with the ID of your own 404 page.

Support for Multilingual Sites

You can define different 404 pages for each language or culture (such as en-us, da-dk, and so on):

"Error404Collection": [
  {
    "Culture": "en-us",
    "ContentKey": "guid-for-english-404"
  },
  {
    "Culture": "da-dk",
    "ContentKey": "guid-for-danish-404"
  }
]

Each entry maps a culture to its specific 404 page using the content’s GUID.

Set a custom 404 page using IContentLastChanceFinder

It is also possible to set up a 404 error page programmatically using IContentLastChanceFinder. To learn more about IContentLastChanceFinder, read the Custom Routing article.

Before following this example, follow the Create a 404 page in the backoffice part. The example below will use the errorPage404 alias of the Document Type to find and display the error page.

1. Create a new .cs file called Error404Page at the root of the project.

2. Add the following code to the newly created class:

Error404Page.cs

using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.Routing;
using Umbraco.Cms.Core.Web;

namespace YourProjectNamespace;

public class Error404Page : IContentLastChanceFinder
{
 private readonly IUmbracoContextAccessor _contextAccessor;

 public Error404Page(IUmbracoContextAccessor contextAccessor)
 {
  _contextAccessor = contextAccessor;
 }

 public Task<bool> TryFindContent(IPublishedRequestBuilder request)
 {
  // In the rare case that an umbracoContext cannot be built from the request,
  // we will not be able to find the page
  if (_contextAccessor.TryGetUmbracoContext(out var umbracoContext) == false)
  {
   return Task.FromResult(false);
  }

  // Find the first notFound page at the root level through the published content cache by its documentTypeAlias
  // You can make this search as complex as you want, you can return different pages based on anything in the original request
  var notFoundPage = umbracoContext.Content?.GetAtRoot().FirstOrDefault(c => c.ContentType.Alias == "errorPage404");
  if (notFoundPage == null)
  {
   return Task.FromResult(false);
  }

  //Set the content on the request and mark our search as successful
  request.SetPublishedContent(notFoundPage);
  request.SetResponseStatus(404);
  return Task.FromResult(true);
 }
}

// ContentFinders need to be registered into the DI container through a composer
public class Mycomposer : IComposer
{
 public void Compose(IUmbracoBuilder builder)
 {
  builder.SetContentLastChanceFinder<Error404Page>();
 }
}

500 Errors

This section guides you in setting up a custom page for handling internal server errors (500 errors) in your Umbraco site. This setup works when:

• A template throws an error.

• A controller throws an unhandled exception.

• A request hits the application, but something fails during rendering or processing.

Create a 500 error page in the Backoffice

1. Go to the Settings section in the Umbraco backoffice.

2. Create a new Document Type with Template called ErrorPage500.

3. [Optional] Add any relevant properties to the Document Type.

4. Click Save.

5. Go to the Templates folder.

6. Add your custom markup and design for the error page in the template. In this case, ErrorPage500.

7. Click Save.

Create a Container for Status Code Pages

1. Create a new Document Type.

2. Name it Statuscodes.

3. Go to the Structure Workspace view.

   • Enable Allow at root.

   • Add the ErrorPage500 Document Type as an Allowed child node types.

   • Click Choose.

4. Click Save.

Add the Content

1. Go to the Content section.

2. Create a new content node based on the Statuscodes Document Type and name it Statuscodes.

3. Click Save or Save and Publish.

4. Under it, create a child node using the ErrorPage500 Document Type.

5. Name it Page 500 or similar.

   • This will be the content shown when a 500 error occurs.

Configure the 500 Error Page Programmatically

To ensure that the 500 page is shown during server errors, you’ll need to configure a custom error controller and route handling.

1. Create a folder called Controllers in the root of your Umbraco project.

2. Add a new file called ErrorController.cs in the Controllers folder.

3. Add the following code to the file:

ErrorController.cs

using Microsoft.AspNetCore.Mvc;

namespace YourProjectNamespace.Controllers;

public class ErrorController : Controller
{
    [Route("Error")]
    public IActionResult Index()
    {
        if (Response.StatusCode == StatusCodes.Status500InternalServerError)
        {
            return Redirect("/statuscodes/500");
        }
        else if (Response.StatusCode != StatusCodes.Status200OK)
        {
            return Redirect("/statuscodes");
        }
        return Redirect("/");
    }
}

Replace YourProjectNamespace with the actual project namespace. In Visual Studio, you can right-click the project and select Sync Namespaces.

1. Add the /error/ route to the list of reserved paths in the appSettings.json file:

appSettings.json

"Umbraco": {
"CMS": {
    "Global": {
    "ReservedPaths": "~/app_plugins/,~/install/,~/mini-profiler-resources/,~/umbraco/,~/error/",
    ...
    }
  }
}

1. Update Program.cs to ensure the error route is triggered by unhandled exceptions:

Program.cs

WebApplication app = builder.Build();

if (builder.Environment.IsDevelopment())
{
    app.UseDeveloperExceptionPage();
}
else
{
    app.UseExceptionHandler("/error");
}

To test locally, replace app.UseDeveloperExceptionPage(); with app.UseExceptionHandler("/error");. Otherwise, you'll get the default .NET error page during development.

Testing Your 500 Error Page

To trigger a 500 error on your site, try introducing a rendering error:

For example, if a Document Type has a property called test, it is normally rendered as:

@Model.Value("test")

To trigger a 500 error, modify it to:

@Model.ValueTest("test")

This will generate a server-side error, allowing you to verify that your custom 500 page is displayed correctly.

Handling app startup failures

When Umbraco fails to start, you may see a blank screen or receive a 500.30 or 502.5 error. These indicate the web application crashed or failed to initialize.

Why can't the app serve an error page?

During startup, Umbraco relies on the ASP.NET Core pipeline. If the app crashes before this pipeline is fully initialized, it can't handle requests or serve custom error pages. That's why you can't rely on Umbraco or ASP.NET Core routing to show error content at this point as it has already failed. For more information, see the Handle errors in ASP.NET Core documentation.

Instead, the web server itself (IIS, NGINX, Apache, and so on) must serve a static fallback 500 page. This page is independent of the application and helps communicate the issue to users when the site is down.

To handle these types of issues:

• Configure your web server (IIS, NGINX, Apache) to serve a static HTML 500 page when the app fails to respond.

• Use uptime monitoring to catch failed starts.

• Check Umbraco logs in App_Data/Logs for startup errors.

Boot Failed Errors

Sometimes you might experience issues with booting up your Umbraco project. This could be a brand new project, or it could be an existing project after an upgrade.

You will be presented with a generic error page when there is an error during boot.

Boot Failed

You can replace the default BootFailed page with a custom static BootFailed.html. Follow the steps below to set it up:

1. Open your project files.

2. Navigate to wwwroot/config/errors

   1. If this folder does not exist already, create it.

3. Add a new file called BootFailed.html.

4. Add your custom markup to the file.

The BootFailed.html page will only be shown if debugging is disabled in the appsettings.json file. Debugging is handled using the Debug key under Umbraco:CMS:Hosting:

appSettings.json

{
    "Umbraco": {
        "CMS": {
            "Hosting": {
                "Debug": false
            }
        }
    }
}

The full error can always be found in the log file.

Are the error pages not working?

If you set up everything correctly and the error pages are not showing correctly, make sure that you are not using

• Custom ContentFinders in your solution,

• Any packages that allow you to customize redirects, or

• Rewrite rules that might interfere with custom error handling.

If your code or any packages configure a custom IContentLastChanceFinder, the settings in appSettings.json will not be used.

Handling errors in ASP.NET Core

For common approaches to handling errors in ASP.NET Core web apps, see the Handle errors in ASP.NET Core article in the Microsoft Documentation.