ImageMagick uses policy.xml to set read/write permissions by file format. When read permissions are disabled for a format such as PDF, ImageMagick operations might fail like:

convert-im6.q16: not authorized

convert-im6.q16: DistributedPixelCache ‘127.0.0.1’

Fix: find policy.xml location at the top of

magick -list policy

for example on Linux it might be at /etc/ImageMagick-*/policy.xml

Edit this policy.xml to have a line like:

<policy domain="coder" rights="read" pattern="PDF" />