Does your application have section access? Nprinting still can't handle that I don't believe. I was getting the same error (see below) but when I tried it with a different app, the connection generated in seconds. So I need to figure out why the connection is crashing for one app, but not the other. I'll let you know if I find anything.
After some time, the connection status will change to 'OK' but the 'cache status remains 'Error - Request has been purged.'
The only issue I see in the log file is in the scheduler log: 'Error withsession method of session manager". Troubleshooting says this could be a license activation issue but I confirmed our license is active. No errors or even new info messages posted to engine or webengine log.
If I try to reload the metadata after the connection status flips to OK, I go back to square 1 with initial 'No Engines are working' connection status.
I had the exactly same error.
I fixed it by changing the document path in the connection to a LOCAL file as the help says in this link: Creating a new app ‒ Qlik NPrinting
Create a connection:
5. Type in the complete path to reach the .qvw in the Document path field.
This is the document path on the computer where the QlikView NPrinting Server is installed.
In this case, use C:\NPrintingServer\QlikViewDocuments\Samples\Sales Demo.qvw
Hope it can help.