How to get rid of PDF permissions issue

Question

Whenever I try to open an outpath.pdf file that I create (like this) :

-- joining PDFs
do shell script quoted form of ("/System/Library/Automator/Combine PDF Pages.action/Contents/MacOS join") & space & "-o" & space & quoted form of outpath & space & quoted form of frontpdfpath & space & quoted form of temppdfpath & space & quoted form of backpdfpath

tell application "Preview"
    activate
    open outpath
end tell

I always get this error message:

The file “outpath.pdf” couldn’t be opened because you don’t have permission to view it. To view or change permissions, select the item in the Finder and choose File > Get Info.

Since this is a PDF that I create on the fly, it's not something that I can do permanently. I already changed the permissions of the folder containing the file and didn't help. Is there something else I can do?

The issue doesn't occur if I manually open the file at least once, close it and then run the script again. Any ideas on why this is happening? and how to fix it?

These are the permissions of the file:

Answer 1

The code proposed by @Caterina :

set sd to path to startup disk
tell application "Preview"
    try
        close sd
    end try
end tell

How it works :

This code clears any sandbox restrictions (sd restrictions set limits on what system resources the script can access/request) that could be there and therefore allows you to have the wanted permissions (no restrains).

Answer 2

I found the solution doing this:

set sd to path to startup disk
tell application "Preview"
    try
        close sd
    end try
end tell

I have no idea why it works, but it does. If anyone has any insight as to why it works feel free to let me know by posting a solution (an I will accept it).