Hello Qlik NPrinting Community,
Qlik has recently taken steps to address an industry wide security vulnerability within the NodeJS library and the Qlik Sense product. When upgrading your Qlik Sense you may need to take steps to update the certificate that is used by NPrinting to communicate with Qlik Sense. Alternatively, If you are a Qlik NPrinting web console user and are encountering the "Error trying to open page" error after a Qlik Sense update you may need to contact your System Administrator.
For all the details on which Qlik Sense releases this affects and the resolution within Qlik NPrinting please review the Knowledge base article posted here https://support.qlik.com/articles/000096879.