convert:not authorized `aaaa` @ error/constitute.c/ReadImage/453

Note: the solution in this and other answers involves disabling safety measures that are there to fix arbitrary code execution vulnerabilities. See for instance this ghostscript-related and this ubuntu-related announcement. Only go forward with these solutions if the input to convert comes from a trusted source.

I use ImageMagick in php (v.7.1) to slice PDF file to images.

First I got errors like:

Exception type: ImagickException

Exception message: not authorized ….. @ error/constitute.c/ReadImage/412

After some changes in /etc/ImageMagick-6/policy.xml I start getting erroes like:

Exception type: ImagickException

Exception message: unable to create temporary file ….. Permission denied @ error/pdf.c/ReadPDFImage/465

My fix:

In file /etc/ImageMagick-6/policy.xml (or /etc/ImageMagick/policy.xml)

1. comment line

   <!-- <policy domain="coder" rights="none" pattern="MVG" /> -->
   

2. change line

   <policy domain="coder" rights="none" pattern="PDF" />
   

   to

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

3. add line

   <policy domain="coder" rights="read|write" pattern="LABEL" />
   

Then restart your web server (nginx, apache).