can't open a PDF on my external

[#1]

I can open PDF's that are saved on my desktop computer but when I try to open a PDF that is on a an external hard drive I get an error that says" There was an error opening this document, access denied". If I move the PDF to my desktop screen it will open.

[#2]

Try to deactivate the Protected Mode: https://community.adobe.com/t5/acrobat-reader/there-was-an-error-opening-this-document-access-denied...