Welcome to Microsoft Q&A,
Thank you for providing detailed information about your environment and the troubleshooting steps you have already performed.
Based on your description, since the issue affects existing users, newly created users, and first-time logons, it may indicate that Windows is not processing the Default App Associations policy at all, rather than there being a problem with a specific file association.
Before abandoning the XML and GPO approach, I recommend checking the following:
1. Verify that the policy is reaching the computer
The policy should create the following registry value:
Registry Key: HKLM\SOFTWARE\Policies\Microsoft\Windows\System
Value Name: DefaultAssociationsConfiguration
If this value is missing, the GPO may not be applying correctly.
Also run: gpresult /h C:\gp.html
Then, verify that Set a default associations configuration file appears under the applied Computer Configuration policies.
2. Verify that the client can access the XML file
Even if the policy is applied, the XML file must be accessible by the target device.
Common causes include:
- Insufficient permissions on the file share
- UNC path unavailable at logon
- SYSVOL replication issues
- DFS namespace or referral issues
As a test, try placing the XML file locally (for example, C:\Windows\AppAssoc.xml) and update the policy to reference the local path. If it works, the issue is likely related to accessing the network location.
3. Review Event Viewer
I would check the following logs next below:
Applications and Services Logs -> Microsoft-> Windows-> Shell-Core -> AppDefaults
Applications and Services Logs -> Microsoft -> Windows -> GroupPolicy -> Operational
These logs may reveal XML parsing errors, invalid associations, file access issues, or Group Policy processing failures.
4. Validate the XML against the target OS version
This is a recommendation exporting the XML from the same Windows build that is being managed.
Common issues include:
- XML exported from an older Windows release
- Feature updates introducing new associations
- Outdated or unsupported association entries
Re-exporting the XML from a fully updated Windows 10/11 reference device is generally recommended.
5. Verify the ProgIDs
Even if the applications are installed, the ProgIDs may differ between application versions.
Examples:
- Adobe Reader vs. Adobe Acrobat
- Chrome Enterprise vs. Consumer Chrome
- Different 7-Zip releases
Consider verifying the registered ProgIDs through:
assoc
ftype
Or by reviewing the relevant entries under HKCR.
6. Check for Intune or MDM conflicts
If the devices are MDM-enrolled or hybrid-joined, MDM-based default application policies can take precedence over Group Policy.
If an ApplicationDefaults CSP policy is configured, it may override the GPO configuration.
7. Confirm the devices are domain-joined
Set a default associations configuration file is intended for domain-joined devices and processes the XML during user sign-in.
If the registry value exists but the associations are still not applied, I would focus on:
- Event Viewer logs
- XML accessibility
- XML validity
- ProgID validation
- Potential MDM policy conflicts
Regarding free alternatives
Unfortunately, there are very few widely adopted, enterprise-scale alternatives that are both free and fully compliant with Microsoft's file association protection mechanisms.
Commonly used approaches today include:
- Microsoft Default App Associations XML + GPO
- Intune ApplicationDefaults CSP
- DISM Import-DefaultAppAssociations (primarily for new profiles)
- SetUserFTA (commercial licensing required for enterprise use)
- Citrix WEM in Citrix environments
Because Windows 10 and later protect file associations through the UserChoice hash mechanism, registry-based methods, Group Policy Preferences registry items, and many custom scripts are typically unreliable and may trigger "An app default was reset" notifications.
At this point, if the policy is failing even for brand-new user profiles, I would expect the next clue to come from the AppDefaults or GroupPolicy event logs rather than the XML file itself.
If you find this information helpful, please consider clicking Accept Answer.
Thank you for using Microsoft Q&A.