In this article, we’ll look at how to manage the default File Type Associations [FTA] on Windows 10/11 and Windows Server 2022/2019/2016. As an example, we will show how to assign a default program to open *.PDF files in Windows, export these settings into an XML configuration file, and deploy the resulting file with file association settings to other computers manually or using Group Policy [GPO].
The main difference between Windows 10/11 and previous Windows versions is that you can’t manage file association settings through the Registry or the “Open With” feature of the Group Policy Preferences. However, there is a new opportunity to export the current settings of file associations from the “reference” computer to an XML file and apply this file to other computers. You can also import a file associations file into a Windows image deployed on your computers [manually, via WDS or SCCM].
How to Change Default Program to Open a File Type on Windows 10 and 11?
Let’s say you want to use Adobe Reader DC to open *.PDF files on your computer. This means you need to associate this file extension with the application. In this example, I’m using a reference computer with Windows 10 22H1 and Acrobat Reader DC installed.
Note that Windows 10 and 11 now have the Microsoft Edge browser installed by default as the default PDF viewer.
To manually create a mapping between
a file extension and a program, go to the Settings -> Default Apps [or run the Settings URI command -> ms-settings:defaultapps] and click the Choose default apps by file type button.
Find the .PDF file type in the list of extensions. Then click on the icon of the program associated with this extension and change the default PDF viewer from Microsoft Edge to Acrobat Reader.
You can automatically assign a specific app with the file extension for which it is registered. To do this, select Set default by apps in the Default Apps section, find your program in the list and click the Manage button.
The next screen contains a list of file types supported by the application. Select the file extensions you want to open with Acrobat Reader.
How to Set File Assertions from the Command Prompt?
On Windows, you can use the assoc command line tool to configure file associations for applications. For example, to check the program that should be used to open PDF files, run the command:
assoc .pdf
In this example, you can see that the AcroExch.Document.DC file type is associated with the PDF file extension:
.pdf=AcroExch.Document.DC
Show all extension associations with file types:
assoc|more
To understand which program the AcroExch.Document.DC file type is associated with:
ftype AcroExch.Document.DC
You can set the type for a specific file type with the command:
ASSOC .csv=txtfile
In this example, we have specified that all CSV files should be opened as plain text files [using notepad.exe by default].
You can create or change the association of a file extension with a program from the command prompt. For example, you want all files with the .tx1 extension to open with notepad++.exe. First, you need to associate the .tx1 extension with the new tx1file file type.
assoc .tx1=tx1file
Now let’s specify the program that should be used by default to open files with the tx1 extension.
ftype tx1file="%programfiles[x86]%\"Notepad++\notepad++.exe" "%1"
You can also use the third-party SetUserFTA tool to assign file associations in Windows. SetUserFTA is a command line utility for quickly setting up file associations [often used on Windows Server 2019/2022 RDS farms to configure file associations with apps].
You can list the current file associations and the ProgID set for them in Windows like this:
SetUserFTA get
To set an association for a specific file extension, use the command:
SetUserFTA.exe extension progid
For example, set Chrome as the default browser for HTML files:
SetUserFTA .http ChromeHTML
SetUserFTA .https ChromeHTML
SetUserFTA .htm ChromeHTML
SetUserFTA .html ChromeHTML
If the application doesn’t have a registered file class or Progid, you can specify its executable. For example:
SetUserFTA .txt applications\notepad++.exe
This is possible for apps registered in the registry key HKEY_CLASSES_ROOT\Applications.
Export and Import Default App Associations on Windows to the XML file
The current file association settings for programs configured under the current user can be exported to an .XML file using DISM:
Dism.exe /online /Export-DefaultAppAssociations:C:\PS\DefaultAssoc.xml
The command exports to an XML file all of your configured program associations. You can open the DefaultAssoc.xml file with any text editor, and see the full list of file associations exported. If you need to use only a part of associations from this list [in order not to override the existing user associations], you can manually edit the XML file. Leave only the lines with the file extensions you need. For example, we’ll leave the following lines for PDF and FDF extensions:
The resulting XML file can be imported into a Windows on other computers using the DISM tool:
Dism.exe /Online /Import-DefaultAppAssociations:C:\PS\DefaultAssoc.xml
Important. These settings to map file extensions to apps will be applied only to new user profiles during at first logon. If you receive an App default reset notification error during the import, check the syntax of the XML file.
You can also import association settings to an offline Windows image in a WIM file [which you use to deploy Windows to new computers]. First, you have to mount the image:
Dism /Mount-Image /ImageFile:C:\mnt\images\install.wim /MountDir:C:\mnt\offline
Then import the XML file:
Dism.exe /Image:C:\mnt\offline /Import-DefaultAppAssociations:\\Server1\Share\DefaultAssoc.xml
Tip. The current file association settings in an offline Windows image can be obtained using this command:
Dism.exe /Image:C:\mnt\offline /Get-DefaultAppAssociations
Configure Default File Associations with Group Policy
In modern versions of Windows, you can use a Group Policy [GPO] option that allows you to apply an XML file with file association settings to all current users of a computer.
For example, you want to apply a group policy with file association settings to all computers in a specific OU [Organizational Unit] of Active Directory.
- Open the Group Policy Management console [
gpmc.msc]; - Find the OU with computers for which you want to apply file associations and create a new GPO;
- Switch to GPO editing mode and go to the section Computer Configuration -> Administrative Templates -> Windows Components -> File Explorer;
- Find the option Set a default associations configuration file;
- Enable the policy and specify the UNC path to your XML file [make sure the path doesn’t contain quotes or spaces] It can be located on a shared network folder, SYSVOL directory on the domain controller, or pre-copied to the computers using GPP or SCCM;
- Restart your computer to apply the new file associations.
The new file association settings will be applied to all users of the computer the next time they sign in.
The path to the XML file with the new file association settings is contained in the DefaultAssociationsConfiguration registry parameter under the key HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\System.
Since Windows 10 tracks changes in the file association settings, the first time you try to open a PDF file, a window may appear confirming the use of Acrobat Reader to open this file type [the prompt appears only once]. Such a request will always appear after installing a new application that is registered to open an existing file type or protocol. You can hide these notifications by enabling the policy “Do not show the ‘new application installed’ notification” under the same GPO section.
When working in Windows, a user can reassign these file associations. However, the next time the Group Policy settings are updated at the next logon, the user’s file associations will be overwritten with the settings from the XML file.
Changing File Association via the Windows Registry
As we said above, in Windows 10 /11the way to set file association options has changed. In the previous section, we showed you how to configure the association for the .pdf file type with an Acrobat Reader through an XML file and Group Policy. Now let’s see how it looks in the Windows registry.
Run the Registry Editor [regedit.exe] and go to the registry key HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\ Explorer\FileExts\.pdf\UserChoice. This registry key contains the association settings for the PDF file extension.
Please note the following registry parameters:
- ProgId – this is the identifier of the registered app to open this file type. This app ID is specified in the XML file. If a long identifier is specified instead of the application name, then the file association with the modern UWP [Metro-style] application is configured. Make sure this UWP app has not been removed from the Windows image;
- Hash – a hash value that is automatically generated to validate the file association with the program. The presence of this hash ensures that the user or administrator [via the GPO] has configured this file mapping. This security mechanism is needed to protect users from malware that can change file associations without the user’s approval.
If you try to manually change the ProgId registry value and assign another program, the Hash value will no longer be valid. In this case, Windows will automatically reset the file association settings to the default state and the user will see a notification:
An app default was reset. An app caused a problem with the default app setting for .html files, so it was reset to Microsoft Edge.
Accordingly, in Windows 10/11 and Windows Server 2022/2019/2016 you won’t be able to configure file associations through the registry, as it worked in Windows 7 and Windows Server 2008R2.
There is a third-party SetUserFTA.exe tool [mentioned earlier] that allows you to calculate the hash and assign a file extension to a program directly through the registry.
How to Reset All File Associations to Default in Windows 10 and 11?
You can reset the previously imported file association settings using the command:
Dism.exe /Online /Remove-DefaultAppAssociations
After running this command, all new users will be logged in with the default file association settings [the reset has no effect on the existing user profiles].
In order to reset the file associations configured manually by the user to the default ones, you need to click on the Reset button in Settings -> Apps -> Default Applications.
This will revert all file associations to a clean Windows 10 state.