If the installed version of Qlik NPrinting 17 is on the service release track, you must upgrade to each successive service release, for example, from 17.0.1 to 17.0.2 to 17.0.3 etc. However, if the installed version is the final service release before a feature (point) release, you may upgrade to the feature release directly, for example, from 17.0.5 to 17.1. if 17.0.5 is the final service release
You must not upgrade from 17.0.5 to 17.2. The previous feature release 17.1 must be installed before upgrading to 17.2 for example.
Your upgrade path is very long since you must upgrade to every intermediary version of NPrinting right up to 17.2.1
One you upgraded each version until you get to NP 17.2.1, then you must upgrade to 17.3.
One you reach 17.3, you can then safely upgrade to the latest release of NPrinting.
Starting from Qlik NPrinting 17.2.1, the Qlik NPrinting Server upgrade process removes RabbitMQ and replace it with the Qlik NPrinting Messaging Service. It is not possible to keep RabbitMQ installed on the same computer of Qlik NPrinting Server 17.2.1 or newer also if it is used by other services than Qlik NPrinting.
Tables are updated differently in early versions (such that you are running NP 17.1.3 of NPrinting which require you to upgrade to each individual general public release and each individual service releases associated with the general release
Now regarding your reported issue:
if you have generated the cache and you still have the message reported, this means you have another failed connection in the NP app which has your successful connection. See this article to resolve: https://support.qlik.com/articles/000056301
If the issue persists, you will need to follow the upgrade process suggested above so you can get working with a supported version of NPrinting. If after upgrading and if the issue still persists while all unsupported items are removed, you should start a support request with Qlik Support or your Qlik Support partner. (please note that the version of NPrinting you are working with has official support ended several years ago.)