Our plugin BSK PDF Manager use ImageMagick to generate thumbnail of a specific page of the PDF and set it as the featured image of the PDF. On some hosting it may met the error of "not authorized" as the following screenshot.
It caused by the security policy that supported by ImageMagick. In this article we only describe how to fix the error and if you want to learn more about the security policy, please visit Solution to ImageMagick "not authorized" PDF Error for more information.
The following instructions require you to have some knowledge about hosting management, you need to connect to your server using SSH and type commands. If you are not familiar with this, please let your hosting support team do it for you.
1. Open the ImageMagick's policy file with vi editor. Generally it locates at /etc/ImageMagick-6/policy.xml .
View this article to check how to use vi to edit and save file.
$ vi /etc/ImageMagick-6/policy.xml
2. Find out the policy about PDF and change the rights to read|write.
Save the file and restart your server or apache service.
Now ImageMagick has changed to use new policy and ImageMagick "not authorized" PDF error has been fixed.