Why can’t I open PDF files on my Android phone?

To fix a PDF file not opening in Adobe reader, you will need to download the latest version of Adobe Reader. After which you will disable the protected mode that comes with it by default. Once this is changed, the issue of the PDF file not opening in Adobe reader will be resolved.

How do I enable PDF viewer?

In Chrome, go to the “Menu” icon, then choose “Settings.” 3. Scroll to the bottom and select “Advanced.” 4. In the “Privacy and Security” section, select “Content settings.” 5. Scroll down and select “PDF documents,” then switch it to “On.”