We have a client who encountered a strange problem when printing certain reports in Nav 2016.
We spent a long time investigating this, and thinking that it was caused by poor performance.
Eventually, we opened a Microsoft ticket. MS suggested that we upgrade .Net to 4.6.1 or above, remove two Windows updates (3098779 and 3097997), and restart the server, and that did actually solve the problem.
Hopefully, this will help someone else if they face the same problem.
The issue occurred quite often, but not always, when printing certain reports (they were all from the Printvis vertical, but that might just be because this client uses Printvis so much). Since these reports are used many times each day, this caused quite some frustration for the users. It only affected users who connect remotely, using CheckPoint VPN and RD Web.
When running the report, the following message appears after a few seconds (5 seconds or less):
"Rendering output for the report failed and the following error occurred: The definition of the report '' is invalid."
When the same user runs the same report, from the same machine, with the same parameters, this message may appear 19 times, then on the 20th attempt the report runs without problem.
The Event Viewer, and the Nav debugger, do not show any relevant messages when this issue occurs.
Re-compiling all objects has helped to reduce the frequency of this error, but it still occurs.