AppContainer Incompatibility in Protected Mode - Adobe Acrobat Reader

Question

After the latest Windows 10 update KB4524098 and KB4525237 Adobe Reader suddenly doesn't start properly anymore, and says:

Adobe Acrobad Reader cannot open inside an AppContainer in Protected Mode due to an incompatibility with your system configuration. Would you like to proceed?

What actually to proceed? Here are the two options it offers:

a) Open Reader with the AppContainer disabled inside Protected Mode

b) Do not open Reader due to the AppContainer system incompatibility

in German:

AppContainer-Inkompatibilität im geschützten Modus

What is actually going on with Adobe? Why is there the need for a "protected mode"? Why is Adobe software not compatible to Windows? And why does the German version of Adobe Reader in its prompt link me to an English incomprehensible "help" page about protected mode troubleshooting ?

Adobe Reader's error prompt window

Answer 1

Could you please check if compatibility settings are applied under Reader shortcut?

1- Find Reader shortcut on the desktop>right-click>Properties

2- Check if the box next to "Run this program in compatibility mode for" is checked.

3- If it is, uncheck the box>click Apply>OK, try opening pdf and see if that works.

Please confirm Acrobat Reader version installed on the machine.

To do so, launch Reader>click Help>select About Adobe Acrobat Reader DC

You may also refer to the following link which discusses the same topic:

https://community.adobe.com/t5/acrobat-reader/adobe-reader-cannot-open-in-protected-mode-due-to-an-incompatability-with-your-system-configuration/td-p/5010848?page=1 .

Keep us posted with the results.