ddclient error when trying to run it as debug to test it
This is a long time passed, but I found a solution to the same issue I had on Ubuntu here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=873750
Adding libjson-any-perl satisfies this dependency.
So did apt-get install libjson-any-perl and now there is no error.
Edit: Cloudflare changed its API version since this was actual which ddclient is not compatible with.