The Fix is in. “404.0 – Not Found” error when printing to Printer from GP 2016 Web Client
“404.0 – Not Found” error when printing to Printer from GP 2016 Web Client – Microsoft Dynamics GP Community
Install, Upgrade & AdminGP 2016
Archived post from 2017. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.