After setting up a domain GPO for default file associations, some users (10 on a total of 5k) still have Edge as default PDF reader.
The file is on a network path. The GPO is applied, and I can see the UNC path in the registry: hklm:\SOFTWARE\Policies\Microsoft\Windows\System pointing to the file I setup via GPO.
On one of the users I found a local gpo pointing to c:\windows\ccm, but after deleting that file a couple of days ago, the issue persists and the file did not reappear. Also modifying the local GPO to point to a local copy of the xml used in the domain GPO does not resolve the issue. Domain GPO should take precedence over local GPO anyways.
Exporting the file associations with DISM for the impacted users: the file does not contain an entry for PDF.
Modifying the exported file to use Adobe Acrobat Reader DC and importing it does not resolve the issue. Exporting it again without logoff/reboot, and the entry for PDF has already disappeared.
Manually setting .PDF in the file associations settings changes default to Adobe Reader DC, but only until next logoff/reboot, then it's back to Edge.
Some of the impacted users are already on Edge chromium, a few are still on Edge legacy.
For the impacted users changing the Edge chromium setting: always open PDF externally gets them in a loop when downloading a PDF, clicking on open results in re-downloading the PDF.
Also tried adding the NoOpenWith regkey in HKEY_CURRENT_USER\SOFTWARE\Classes\AppX4hxtad77fbk3jkkeerkrm0ze94wjf3s9, which is not resolving the issue.
Ran a procmon at boot, but couldn't find an XML which sets another default association. Also the OEMdefaultassociations.xml in System32 does not contain an entry for PDF. Adding manually does not resolve the issue.
Impacted users are in different OU's, no other GPO's pushing default XML associations, are on different winver's: 1903 - 1909 - 2004
I have officially ran out of possible solutions. What is causing this issue, please? Are there other XML's which could be applying or are there other registry locations to check? Thanks in advance.
Delete this registry key (search in regedit for the sentence "Microsoft Edge PDF Document"):