Authorization Error : PDF to Image not allowed by ImageMagick

For some time ImageMagick adopted a security policy. It has become a little more rigorous with ImageMagick itself and Linux distributions included. Here is the Quick and easy solution. Run the following code in the terminal:

sudo mv /etc/ImageMagick-6/policy.xml /etc/ImageMagick-6/

When done, you can restore the original with

sudo mv /etc/ImageMagick-6/ /etc/ImageMagick-6/policy.xml