It could be issues in your network connectivity (WiFi, DNS, etc).
Try the "RPC quickfixes" paragraph:
The RPC error always occurs when the QV desktop is closed during the processing of any NPrinting report.
Note: NPrinting sends API calls to the QV desktop and thus the QV desktop does the heavy lifting in the processing of an NP report. You must leave the QV desktop open.
Further if you do no have the QV desktop installed with your NP designer, server or QV server, then you must also do so.
If another process is closing your QV desktop during the processing of a NP report, you must address the process which is shutting down the QV desktop to ensure the QV desktop is left open.
I too am having the same problems. And also I am not running any other QV except the one NP Design is calling on.
This is our DEV server with QV and NP Services running using different Server IDs. The NP designer 16 R3 and QV 11.2 R13 desktop are both on this server.
I am in the NP Excel Report template editor and when I try and change Margins, I get the error Window RPC and can not close the editor until I go into the Task manager and end NP Designer.
Any other work around I can try to solve this issue?