For once I am stumped by a Revit 2017 error...
I have recently found an error that prohibits you from saving or closing a Revit project for a very random reason. Revit Recess readers, any ideas?
Changing the duct system calculation methods from All, Flow Only, Performance, to None did not change the situation. In this case, I demonstrated selecting a Cold Water System by using the <TAB> key, to my students. After exciting the command, the error still remained. Revit is updated: 17.0.1117.0 / 20170118_1100(x64) / 2017.2. We had the "Background Processes" run for about an hour an a half, with no success in saving or closing the file.
A little tip: Provide as much information as possible on any support case. This will enable either your Reseller, or Autodesk's Support Team to pinpoint the exact cause of the problem. .