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Updated Mar 01, 2018.

Setting the Default PDF Viewer

Since 10.x, it has been possible to have both Acrobat and Reader on the same machine.

The default handler can be set in the following ways:


Property usage evolves over major releases. For details, see Adobe Properties.

Windows 8-10

System requirements

  • Acrobat and Acrobat Reader 11.x
  • Supported Platforms: Windows 8 and above

The problem

Admins often want to reliably set Acrobat and Reader as the default PDF owners on their organization’s desktops. Since Windows 8, it has become more difficult for applications to take ownership of certain filetypes. Even when admins have a method for setting a default handler (described above), once the application is installed end users can change the file type associations via the Control Panel or with Right Click > Open With. Additionally, other applications sometimes force Windows to show an application selection dialog when a user clicks on a file, thereby allowing users to select a different application for that file type. Thus, since Windows 8, admins have little control over file type associations after installing an application.

Solution 1: DSIM

Deployment Image Servicing and Management (DISM) is a way to enforce file type associations. While it remains difficult to prevent users from selecting alternative default applications, Microsoft addresses this problem by providing DISM as a way for admins to reinstate the defaults when a user logs off and on.

While DISM is a command-line tool that is used to mount and service Windows images before deployment, it can also be used to set file type owners on Windows 8 and above. Admins can use the default application association-servicing commands to import, export, list, and remove the settings that specify which application opens a file based on the file name extension or protocol. Microsoft provides many DSIM command line options for performing these steps.

Solution 2: GPO policy

You can also enforce the filetype via GPO policies. Using Group policy admins can force file associations each time a user logs in. This way even if a user changes the default PDF handler in a particular session or an OS update changes it, the next time the user logs in, it will be changed back to what the admin has specified.

To set the file handler via a GPO:

  1. Download the sample file association files. These files include all the file types supported by Acrobat and Reader. To create your own XML files:

    1. Run an elevated command prompt on a machine that has your default application set correctly.
    2. Type Dism /Online /Export-DefaultAppAssociations:<XML path>\AppAssoc.xml. This creates an XML file that has all your file types and their current associations.
    3. Edit the XML file to include only the file associations that you wish to enforce.


You can create different files for different groups in your organization. For example, you can have one group that has Adobe Reader set as default and another that uses Adobe Acrobat.

  1. Place this XML on a shared network location or push this XML to all your machine-specific locations via a script. For example, C:\Windows\System32 (do not use a user-specific location).

  2. Set the XML configured with your preferences in a Windows 8 Group Policy setting, and enable the setting as follows:

    1. Open up the Group Policy MMC (open a command prompt and type gpedit.msc) on your Server 2012 instance.
    2. Locate the policy under Computer Configuration\Administrative Templates\Windows Components\File Explorer\Set a default associations configuration file. This policy specifies the path for the XML file that can be either stored locally or on a network location.
    3. Enable the policy, and specify the location where you have stored the XML file. The corresponding registry entry is HKLM\Software\Policies\Microsoft\Windows\System\DefaultAssociationsConfiguration.

File associations will now be enforced on user logon.

Local Group Policy Editor


Set a file association configuration file



  1. The end user machine needs to be domain-joined for this method to work.
  2. Users can change the file associations during the current session. However, admin settings are reinstated at next logon.
  3. As of 5th Feb 2016, it is a known limitation of Windows 10 that when new user is created on the machine after enforcing the GPO Policy, then on first login ownership is not set. However, the correct settings are applied on subsequent logins.

Affected ProgIDs for various products

Adobe Acrobat 11.x
File Type ProgID
.pdf Acrobat.Document.11
.pdfxml Acrobat.pdfxml
.acrobatsecuritysettings Acrobat.acrobatsecuritysettings
.fdf Acrobat.FDFDoc
.xfdf Acrobat.XFDFDoc
.xdp Acrobat.XDPDoc
.pdx PDXFileType
.api Acrobat.Plugin
.secstore Acrobat.SecStore
.sequ Acrobat.Sequence
.rmf Acrobat.RMFFile
.bpdx AcrobatBPDXFileType

10.x and earlier

Default behavior

Prior to 10.x, Adobe did not recommend or support having both applications installed on the same system. If you do deploy both applications, the installer sets Acrobat as the default PDF viewer by default since it is the more functional of the two applications. In general, Acrobat was more capable and Reader was more secure.

Locking the PDF viewer

Admins can prevent end users from changing the setting by using the HKLM feature lockdown preference DisablePDFHandlerSwitching.


This does not prevent users from changing PDF ownership using Windows Explorer.