Set default app associations via Windows 10 MDM

This blog post will be about setting default app associations, or file type associations, on Windows 10 devices. Starting with Windows 10, version 1703, it’s possible to set the default app associations via Windows 10 MDM. In this post I’ll briefly go through this setting and I’ll show how to configure the setting via Microsoft Intune hybrid and Microsoft Intune standalone. I’ll end this post by showing the end-user experience.

Configuration

Starting with Windows 10, version 1703, a new setting was introduced that allows an administrator to set the default file type and protocol associations. When set, default associations will be applied on sign-in to the PC. Every sign-in. In other words, the end-user can make adjustments. However, once the end-user signs-out and signs-in again, the default associations will be applied again. This does require the PC to be Azure AD joined.

Get the required information

Let’s start by getting the required information to configure the custom OMA-URI setting. The required OMA-URI setting is available in the Policy CSP.

OMA-URI setting: ./Vendor/MSFT/Policy/Config/ApplicationDefaults/DefaultAssociationsConfiguration

The required OMA-URI value requires the following steps to get it in the correct format.

1	On Windows 10, version 1703, navigate to Settings > Apps > Default apps and configure the required default apps;
2	Open Command Prompt and run DISM /Online /Export-DefaultAppAssociations:DefAppAss.xml to export a required app associations file;
3	Open your favorite Base64 encoder and encode the content of DefAppAss.xml to Base64 format. In my example I was only interested in switching to Internet Explorer as the default browser and keeping Microsoft Edge as the default for PDF reading. That allowed me to remove all the remaining content from the DefAppAss.xml. Then I used base64encode.org to easily encode the remaining content of the DefAppAss.xml to Base64 format (see screenshot).
4	The result in Base64 format is the OMA-URI value.

Configure the setting

After getting the required information, let’s have a closer look at the configuration of the setting. The setting can be used in Microsoft Intune hybrid and Microsoft Intune standalone, by using the configuration guidelines shown below.

Environment	Configuration guidelines
Microsoft Intune hybrid	The configuration in Microsoft Intune hybrid can be performed by starting the Create Configuration Item Wizard in the Configuration Manager administration console. Make sure to select Windows 8.1 and Windows 10 (below Settings for devices managed without the Configuration Manager client) on the General page and to select Windows 10 on the Supported Platforms page. Now select Configure additional settings that are not in the default setting groups on the Device Settings page and the configuration can begin by using the earlier mentioned OMA-URI setting and value. Once the configurations are finished, the created configuration items can be added to a configuration baseline and can be deployed to Windows 10 devices.
Microsoft Intune standalone (Azure portal)	The configuration in Microsoft Intune standalone, in the Azure portal, can be performed by creating a Device configuration. Create a new profile, or add a row to an existing custom profile. With a new profile, make sure to select Windows 10 and later as Platform and Custom as Profile type. In the Custom OMA-URI Settings blade, add the custom settings by using the earlier mentioned OMA-URI setting and value. Once the configurations are finished, the profile can be saved and can be deployed to Windows 10 devices.

Note: This post is based on the custom OMA-URI settings configuration. At some point in time this configuration can come available via the UI of Microsoft Intune standalone and/or hybrid.

End-user experience

Now let’s end this post by having a quick look at the end-user experience. Below on the left is the default Windows configuration and below on the right is the applied policy with the custom app associations. I know that this doesn’t provide a lot of information. However, it does show one important fact, which is that there is nothing preventing the end-user from making adjustments. The end-user can still make adjustments, but those adjustments will be reverted during the next sign-in.

More information

For more information about the Policy CSP, please refer to this article about the Policy CSP.