Implementing Custom Error Pages

Umbraco is built upon Microsoft's .NET Framework and is using ASP.NET. This provides a number of options when setting up custom error pages on your website.

Custom error handling might make your site look more on-brand and minimize the impact of errors on user experience. An example, a custom 404 with some helpful links (or a search function) could bring some value to the site.

Contents

This article contains guides on how to create custom error pages for the following types of errors:

• 404 errors ("Page not found")

• Maintenance Page

In-code error page handling

One way is to watch for error events and serve corresponding pages via C# code.

404 errors

In this method we will use a 404 page created via the backoffice.

Create a 404 page in the backoffice

First, create a new Document Type (though you could also use a more generic Document Type if you already have one) called Page404. Make sure the permissions are set to create it under Content. Properties on this Document Type are optional - in most cases, the 404 not found page would be static. Make sure to assign (and fill out) the template for your error page, and then create it in Content.

Set a custom 404 page in appsettings.json

Once all of that is done, grab your published error page's ID, GUID or path and head on over to the appsettings.json.

The value for error pages can be:

• A content item's GUID ID (example: 26C1D84F-C900-4D53-B167-E25CC489DAC8)

• An XPath statement (example: //errorPages[@nodeName='My cool error']

• A content item's integer ID (example: 1234)

That is where the value you grabbed earlier comes in. Fill it out like so:

{
    "Umbraco": {
        "CMS": {
            "Content": {
                "Error404Collection": [
                    {
                        "Culture": "default",
                        "ContentKey": "81dbb860-a2e3-49df-9a1c-2e04a8012c03"
                    }
                ]
            }
        }
    }
}

The above sample uses a GUID value.

With this approach, you can set different 404 pages for different languages (cultures) - such as en-us, it etc.

If you are hosting your site on Umbraco Cloud, the best approach would be using an XPath statement. This is because content IDs might differ across Cloud environments.

XPath example:

{
    "Umbraco": {
        "CMS": {
            "Content": {
                "Error404Collection": [
                    {
                        "Culture": "default",
                        "ContentXPath": "//errorPages[@nodeName='My cool error']"
                    }
                ]
            }
        }
    }
}

In the above XPath example //errorPages is the DocTypeAlias

Errors with booting a project

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.

When there is an error during boot you will presented with a generic error page.

Boot Failed. Umbraco failed to boot, if you are the owner of the website please see the log file for more details.

In order to customize this error page it is recommend that you create a new HTML file using the name BootFailed.html. The file must be in a folder config/errors in the wwwroot on the Physical file system.

The BootFailed.html page will only be shown if debugging is disabled in the appsettings.json file i.e.

{
    "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 in web.config that might interfere with custom error handling.

If your code or any packages configures a custom IContentLastChanceFinder, the settings 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.

Maintenance Page

While upgrading Umbraco in the past it would redirect visitors of the website to the upgrading page.

To prevent this we have added a maintenance page that will be shown when visiting the website while Umbraco is in Upgrade runtime mode.

Maintenance page

It is possible to disable the maintenance page as most upgrades can be done without the website having to restart or go down.

To disable the maintenance page, add the following configuration in the appSettings.json file:

{
    "Umbraco": {
        "CMS": {
            "global": {
                "ShowMaintenancePageWhenInUpgradeState": false
            }
        }
    }
}

To customize the Maintenance page, in the Umbraco folder create a new folder called: UmbracoWebsite.

in this folder create a new file called maintenance.cshtml.

Once the file has been created you can style it so it looks the way you want it to.

It is not recommended to let Umbraco be in Upgrade mode for longer periods. Most migrations can be executed while the website continues to work. Consider using this feature, if you know what you are doing.