Adobe Acrobat Reader Cannot Open in Protected Mode

What is Protected Mode?

Protected Mode continues to be Adobe's primary defense-in-depth security strategy for mitigating and preventing security vulnerabilities. Protected Mode protects you by limiting what malicious files can do and access. Protected Mode is enabled by default in Acrobat Reader, and is designed to run transparently in the background while protecting your hardware and data.

More information

This document lists what Protected Mode does not support as well as changes across releases. To learn more about sandboxing and protected mode, see the following:

For FAQs and information about registry configuration and creating custom policies, see the Protected Mode chapter in the Application Security Guide.
Find architectural-level details in the ASSET team's blog.

Antivirus software conflicts

By default, Acrobat Reader runs in Protected Mode. In certain situations, Adobe Acrobat or Acrobat Reader experiences compatibility issues with anti-virus software when that software intercepts some system calls for the Adobe Acrobat or Acrobat Reader sandbox. In these cases, Adobe Acrobat or Acrobat Reader could fail to open, crash, or displays an incompatible configuration dialog.

For example, Protected Mode is known to be incompatible with:

Trend Micro antivirus version 15 or earlier. Adobe recommends you update to the Trend Micro version 16 or higher. For more information, see Can't verify your subscription status | Acrobat, Trend Micro Antivirus.
Kaspersky Security for Virtualization 5.1 Light Agent can cause Adobe Acrobat or Acrobat Reader to crash when Protected Mode is enabled.
Palo Alto's Traps version 5 or lower causes Adobe Acrobat or Acrobat Reader to crash when the Protected Mode is enabled. Adobe recommends you update to the latest version of traps.
Some Symantec Endpoint Protection configurations. Adobe recommends that users update to Symantec Endpoint Protection 11.0 RU6 MP2 or higher.

Adobe is working with anti-virus companies to resolve these problems.

Third-party plugin conflicts

Protected Mode restricts certain file and registry operations that might break some functionalities of third-party plugins. In such a case, update the plugin, or contact the plugin vendor.

Protected Mode is known to be incompatible with the following third-party plugins:

iManage
Heidelberg
Enfocus PitStop
PDFLib
Common Look PDF Validator
PfxEngagement by Wolters Kluwer

Adobe is working with the plugin vendors to resolve the problems.

Some plugin vendors might ask you to disable Protected Mode in Adobe Acrobat or Acrobat Reader while using their plugins. Adobe does not recommend disabling Protected Mode permanently. It is highly recommended to enable Protected Mode in Adobe Acrobat or Acrobat Reader after your workflow is complete.

Other issues

You might encounter any of the following issues when you enable the Protected Mode in Adobe Acrobat or Acrobat Reader:

Cannot render 3D PDF hardware acceleration with NVidia graphics.
Unable to paste in JavaScript debugger or Document Properties window if the copied content contains RTF format.
Cannot extract pages using drag-and-drop to explorer.
Unable to record a sound annotation.

P11 smart card workaround

The installation of some smart cards doesn't work for Adobe Acrobat or Acrobat Reader users when in Protected Mode. Because Protected Mode sandboxes certain processes that make system calls, smart card installation can fail or result in the "unsupported configuration" dialog appearing. However, a simple workaround is available. Install the smart card software with Protected Mode turned off as follows:

Disable Protected Mode by going to Edit > Preferences > Security (Enhanced) and deselectingEnable Protected Mode at startup.

Restart Adobe Acrobat or Acrobat Reader.

Install the smart card software according to the provider's instructions.

Restart Adobe Acrobat or Acrobat Reader.

Adobe Acrobat Reader Cannot Open in Protected Mode

Source: https://helpx.adobe.com/acrobat/kb/protected-mode-troubleshooting-reader.html#:~:text=Disable%20Protected%20Mode%20by%20going,Adobe%20Acrobat%20or%20Acrobat%20Reader.&text=Enable%20Protected%20Mode.,Adobe%20Acrobat%20or%20Acrobat%20Reader.