PDF files do not open in Adobe Acrobat Reader

Question / Problem

I'm trying to open a PDF file, but Adobe Acrobat Reader does not open it.

Answer / Solution

The reason why PDF files cannot be opened is because Adobe Acrobate Reader is preventing to open files from an application with administrator rights via its Protected Mode. To solve this issue disable protected mode by doing the following:

1. Open Adobe Reader.
2. Choose Edit > Preferences...
3. In the Categories list on the left, select Security (Enhanced).
4. In the Sandbox Protections section, deselect Enable Protected Mode at startup.
5. Click OK to save the changes.
6. Close Adobe Reader.

For more information about Protected Mode (and possible vulnerabilities) refer to the Adobe website.