What Is an ADMX File?

How to open Windows/Office Group Policy Settings files

A file with the ADMX file extension is a Windows/Office Group Policy Settings XML-based file that serves as a replacement for the older ADM file type.

Introduced in Windows Vista and Windows Server 2008, ADMX files, sometimes called Administrative Template XML-Based files, specify which registry keys in the Windows Registry are changed when a certain Group Policy setting is changed.

For example, one ADMX file might prevent users from accessing Internet Explorer. The information for this block is located in the ADMX file which in turn is reflected in the registry.

several ADMX files in Windows 10

How to Open an ADMX File

ADMX files are structured the same as XML files and so you can follow the same open/edit rules. In other words, any text editor, like Notepad in Windows or the free Notepad++, will open ADMX files for viewing and editing.

If you're using a Mac or Linux computer to read or edit the ADMX file, Brackets or Sublime Text might work, too.

Microsoft's ADMX Migrator tool is a free add-on to the Microsoft Management Console (MMC) that provides a GUI to edit ADMX files instead of you having to use a text editor.

Viewing an ADMX file using a text editor is for that purpose only—to view the ADMX file. You don't need to open ADMX files manually for them to be used because the Group Policy Management Console or Group Policy Object Editor is what actually utilizes the files.

ADMX files are located in the C:\Windows\PolicyDefinitions\ folder in Windows. To import ADMX files, copy them to that folder.

To display policy settings in a specific language, ADMX files reference language-specific resource files (ADML files) in a subfolder in the same location. For example, US English Windows installs use the en-US subfolder to hold ADML files.

If you're on a domain, use this folder instead:

C:\Windows\SYSVOL\sysvol\[your domain]\Policies

How to Convert an ADMX File

There aren't any clear reasons, or means for that matter, to convert an ADMX file to another file format. However, you may be interested in converting another type of file to an ADMX file.

In addition to editing ADMX files, the free ADMX Migrator tool from Microsoft can convert files from ADM to ADMX.

Since ADMX files define which registry keys should be changed in order to apply a Group Policy setting, it would follow that you could convert REG files to a format that could be used by Group Policy. That procedure uses a script in Microsoft's Visual Studio program to convert REG to ADMX and ADML.

More Information on ADMX Files

Group Policy Object Editor in versions of Windows and Windows Server prior to Vista and Server 2008 are unable to display ADMX files. However, all operating systems that use Group Policy are able to work with the older ADM format.

Internet Explorer template files are stored in a file called inetres.admx. You can download Internet Explorer Administrative Templates from Microsoft, too.

Microsoft no longer supports Internet Explorer and recommends that you update to the newer Edge browser. Head to their site to download the newest version.

Still Can't Open the File?

The first thing you should check for if the file isn't opening with any of the suggestions above, is that the file extension actually does read as ".ADMX" and not just something that looks similar.

For example, ADX is often confused for ADMX, but that's used for Approach Index files or ADX Audio files; neither of which have anything to do with Group Policy or the XML format in general. If you have an ADX file, it either opens with IBM's Lotus Approach or is played as an audio file using FFmpeg.

ADP is another one that could be confused for this file extension even though it's entirely unrelated.

If it's not clear already, the idea here is to just make sure that the file you're trying to open is actually using a file extension supported by the software. If you don't really have an ADMX file, then research the file's true extension to learn more about which programs can open or convert it.

  • Where is the default location for ADMX files?

    ADMX files store in the default PolicyDefinitions folder on Windows PCs. To create a central location for ADMX files in a Windows domain environment, copy the contents of the default PolicyDefinitions folder and place it in a new PolicyDefinitions folder in SYSVOL\Your_Domain\Policies on the domain controller. Learn more about creating and using a Central Store for all domain controllers in a Windows domain.

  • How do I edit a Local Group Policy using an ADMX file?

    Open the Local Group Policy Object Editor from Run > gpedit.msc > OK. Select the Local Group Policy object to edit > the policy setting to adjust beneath Administrative Templates > and the policy setting to change from the Setting column. Double-click the policy setting > choose Not ConfiguredEnabled, or Disabled > and click OK to apply your edits.

Was this page helpful?