How do I resolve this InvalidOperationException while attempting Revit to PDF Conversion?

I am trying to automate the process of PDF printing in Revit 2017 using Revit API with Idling event handler. I am opening the Revit document using OpenDocumentFile method and not using ActiveUIDocument anywhere. This process is generating InvalidOperationException. I am not sure why is it giving the exception or whether it is allowed using Revit API.

Journal Output:

    ' 1:< 0 <-pushSettingsIntoDriver 
    ' C 27-Sep-2016 14:45:22.641;   1:< ExportToRequestedFormat() : Pdf Print Exception : InvalidOperationExceptionAt least one view from the view set could not be printed.
    ' at Autodesk.Revit.DB.Document.Print(ViewSet views, View viewTemplate, Boolean useCurrentPrintSettings)
    ' at Autodesk.Revit.DB.Document.Print(ViewSet views, Boolean useCurrentPrintSettings)
    ' at RevitCommandListener.RevitCommandListenerService.ExportToRequestedFormat(UIApplication uiapp) 

Code Behind:

     using (FilteredElementCollector viewCollector = new FilteredElementCollector(doc))
     {
           ViewSet set = new ViewSet();
           ElementClassFilter viewFilter = null;
           PrintManager pm = PrinterDriverSettings.GetPrintManager(doc, _ifcSaveFile, PrinterDriver.Bullzip);
    
           switch (_pdfExportSetting)
           {
               case PDFExportOptions.SheetsOnly:
                    viewFilter = new ElementClassFilter(typeof(Autodesk.Revit.DB.ViewSheet));
                    viewCollector.WherePasses(viewFilter);
    
                    foreach (Autodesk.Revit.DB.ViewSheet vw in viewCollector)
                    {
                          if (vw.CanBePrinted && !vw.IsTemplate)
                               set.Insert(vw);
                    }
                    break;
    
               case PDFExportOptions.ViewsOnly:
                    viewFilter = new ElementClassFilter(typeof(Autodesk.Revit.DB.View));
                    viewCollector.WherePasses(viewFilter);
    
                    foreach (Autodesk.Revit.DB.View vw in viewCollector)
                    {
                          if (vw.CanBePrinted  && !vw.IsTemplate && !(vw.GetType() == typeof(ViewSheet))) //Skip sheets
                              set.Insert(vw);
                    }
                          break;
    
    
               case PDFExportOptions.ViewsAndSheets:
     
                    viewFilter = new ElementClassFilter(typeof(Autodesk.Revit.DB.View));
                    viewCollector.WherePasses(viewFilter);
    
                    foreach (Autodesk.Revit.DB.View vw in viewCollector)
                    {
                        if (vw.CanBePrinted  && !vw.IsTemplate)
                             set.Insert(vw);
                    }
                    break;
    
                case PDFExportOptions.Sections:
                     viewFilter = new ElementClassFilter(typeof(Autodesk.Revit.DB.ViewSection));
                     viewCollector.WherePasses(viewFilter);
                     foreach (Autodesk.Revit.DB.ViewSection vw in viewCollector)
                     {
                          if (vw.CanBePrinted &&  && !vw.IsTemplate !(vw.ViewType == ViewType.Elevation))
                             set.Insert(vw);
                     }
    
                     break;
    
                case PDFExportOptions.Elevations:
                     viewFilter = new ElementClassFilter(typeof(Autodesk.Revit.DB.ViewSection));
                     viewCollector.WherePasses(viewFilter);
    
                     foreach (Autodesk.Revit.DB.ViewSection vw in viewCollector)
                     {
                          if (vw.CanBePrinted  && !vw.IsTemplate && vw.ViewType == ViewType.Elevation)
                          {
                               set.Insert(vw);
                          }
    
                      }
                      break;
    
                 case PDFExportOptions.Schedules:
                      viewFilter = new ElementClassFilter(typeof(ViewSchedule));
                      viewCollector.WherePasses(viewFilter);
    
                      foreach (ViewSchedule vw in viewCollector)
                      {
                           if (vw.CanBePrinted && !vw.IsTemplate)
                                set.Insert(vw);
                      }
                      break;
                   }
    
                   if (_pdfExportSetting != PDFExportOptions.None && set.Size > 0)
                   {
                        Transaction tr = new Transaction(doc, "tr_pdf_print");
    
                            try
                            {
                                 tr.Start();
                                 doc.Print(set, true);
                                 tr.Commit();
                            }
                            catch(Autodesk.Revit.Exceptions.InvalidOperationException iopex)
                            {
                                    uiapp.Application.WriteJournalComment("ExportToRequestedFormat() : Pdf Print Exception : InvalidOperationException" + iopex.Message + Environment.NewLine + iopex.StackTrace, true);
                            }
                                catch(Autodesk.Revit.Exceptions.ArgumentNullException argsex)
                            {
                                    uiapp.Application.WriteJournalComment("ExportToRequestedFormat() : Pdf Print Exception : ArgumentNullException" + argsex.Message + Environment.NewLine + argsex.StackTrace, true);
                            }
                                catch(Autodesk.Revit.Exceptions.ArgumentException arex)
                            {
                                    uiapp.Application.WriteJournalComment("ExportToRequestedFormat() : Pdf Print Exception : ArgumentException" + arex.Message + Environment.NewLine + arex.StackTrace, true);
                            }
                                catch(Autodesk.Revit.Exceptions.ApplicationException appex)
                            {
                                    uiapp.Application.WriteJournalComment("ExportToRequestedFormat() : Pdf Print Exception : ApplicationException" + appex.Message + Environment.NewLine + appex.StackTrace, true);
                            }
                            finally
                            {
                                set.Dispose();
                                viewFilter.Dispose();
                                viewCollector.Dispose();
                                pm.Dispose();
                                tr.Dispose();
                            }

                    } 

In addition to the IsPrintable field, the other thing you'll need to check for is whether the View is actually a View Template. Use IsTemplate to check that.