Greetings, Mason! Thank you for the information. I wasn't certain if the installation method would affect how the matter should be resolved. Yesterday, I ran the following command, and the results confirmed the module's origins, as you suspected: $ sudo dpkg -s libjson-validator-perl Package: libjson-validator-perl Status: install ok installed Priority: optional Section: perl Installed-Size: 421 Maintainer: ***** Architecture: all Version: 5.02-1 Depends: perl (>= 5.25.1), libmojolicious-perl (>= 7.28), libyaml-libyaml-perl (>= 0.67) Description: Validate data against a JSON schema (no description was found) . This description was automagically extracted from the module by dh-make-perl. Homepage: https://metacpan.org/release/JSON-Validator Your suggested resolution worked perfectly, and I hope now that our server is on the right track. I do wonder, however, if there are other modules that were installed separately. I may have to engage in a hunt.