I tried to convert a few PNG files to a PDF file using ImageMagick's covert tool as described here. That threw up this error:
$ convert *.png out.pdf convert-im6.q16: not authorized `out.pdf' @ error/constitute.c/WriteImage/1037.
Since ImageMagick is sometimes used on web servers to operate on images for users, it has security checks on certain operations. The above error was caused since my operation failed one of its policies.
Since I am doing these operations locally, I do not really want ImageMagick imposing security policies. So I moved its policy file so that it is not used:
$ sudo mv /etc/ImageMagick-6/policy.xml /etc/ImageMagick-6/policy.xml.orig
My conversion worked after this change.
Tried with: ImageMagick 6.9.7 and Ubuntu 18.04