Internet Explorer add-on is automatically disabled when Acrobat Reader DC runs

[Kastel]

I'm developing a HTML application (HTA) that shows PDF within its iframe. For this functionality, Acrobat Reader IE add-on must be enabled.

However I found that the IE add-on is disabled when standalone Acrobat Reader DC is run.

I have reproduced the problem by following order:

1. Open IE 11, open add-on menu, find "Adobe PDF Reader", and enables it.
2. Run Acrobat Reader DC (standalone program)
3. Open IE 11, open add-on menu, and "Adobe PDF Reader" is now disabled.

It seems apparent that when Acrobat Reader DC is run, it somehow disables IE plugin.

I have tried many suggested solutions to fix it.

I have changed "Internet" options of Acrobat Reader DC preferences: I checked all, and uncheked all, but nothing happened.

Enhanced Protected Mode of IE advanced preferences is cleared.

I even cleared acrobat installation using cleaner tool and reinstalled it. But this problem persists.

OS: Windows 10

Acrobat Reader DC version: 2018.009.20044

IE version: 11.251.16299.0

[Kastel]

I have managed to fix it by myself, so I left additional comment as a self-answer.

Actually the problem itself is not fixed as I failed to stop Acrobat Reader DC to disable the IE 11 add-on.

Instead, I managed to make the add-on permanently enabled by Windows group policy.

https://docs.microsoft.com/en-us/internet-explorer/ie11-deploy-guide/enable-and-disable-add-ons-usin...

Enable and disable add-ons using administrative templates and group policy (Internet Explorer 11 for...

> "Using the CLSID and Administrative Templates to manage group policy object"

I put CLSID of Adobe PDF Reader add-on into the group policy's Add-on List and set its value as 1. This made Adobe PDF Reader to be enabled permanently and not would be disabled by Acrobat Reader DC standalone.

Still, I can't understand why standalone reader program silently disables a browser plugin. But this can be a remedy for me now.

---------

PROBLEM NOT SOLVED.

Although the add-on is enabled permanently in the add-on manage menu, it actually not working. Acrobat Reader DC somehow still deactivates the add-on.

Still need Adobe's and other experts help.

[Kastel]

Anyone keep track on it so I must post another possible self-answer to here.

As IE 11 add-on is disabled by registry, I tried to lock the registry value by permission.

When I visited "\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Ext\Settings\", there was no key for Adobe PDF Reader add-on. I'm not sure about this is normal.

So I added a new key with name "{CA8A9780-280D-11CF-A24D-444553540000}" and added a DWORD value "flag" under that key, left its value to 0. and I edited key permission to deny all permissions of that key for every single Windows account in my PC.

This may prevent Acrobat Reader DC to intervene into IE 11 settings to disable the add-on, and looks fine for me now.

I'll come back later with follow-ups.