I tried the following and it worked for me. Cool routine, by the way.
Code:
Sub ExportPDF()
'UpdatebyExtendoffice20181120
Dim I As Long
Dim xDlg As FileDialog
Dim xFolder As Variant
Dim xStart As Integer, xEnd As Integer
ActiveDocument.ComputeStatistics (wdStatisticPages)
'MsgBox "Page count = " & ActiveDocument.BuiltInDocumentProperties(wdPropertyPages)
On Error GoTo lbl
Set xDlg = Application.FileDialog(msoFileDialogFolderPicker)
If xDlg.Show <> -1 Then Exit Sub
xFolder = xDlg.SelectedItems(1)
xStart = CInt(InputBox("Start Page", "PDF Export"))
xEnd = CInt(InputBox("End Page:", "PDF Export"))
If ActiveDocument.BuiltInDocumentProperties(wdPropertyPages) < xEnd Then
MsgBox "End page is more than total pages."
Exit Sub
End If
If xStart <= xEnd Then
If Int((xEnd + 1 - xStart) / 2) <> (xEnd + 1 - xStart) / 2 Then
MsgBox "Start and end pages does not include an even number of pages."
Exit Sub
End If
For I = xStart To xEnd Step 2
ActiveDocument.ExportAsFixedFormat OutputFileName:= _
xFolder & "\Page_" & I & "_and_" & I + 1 & ".pdf", ExportFormat:=wdExportFormatPDF, _
OpenAfterExport:=False, OptimizeFor:=wdExportOptimizeForPrint, Range:= _
wdExportFromTo, From:=I, To:=I + 1, Item:=wdExportDocumentContent, _
IncludeDocProps:=False, KeepIRM:=False, CreateBookmarks:= _
wdExportCreateHeadingBookmarks, DocStructureTags:=True, _
BitmapMissingFonts:=False, UseISO19005_1:=False
Next
End If
Exit Sub
lbl:
MsgBox "Enter right page number", vbInformation, "PDF Export"
End Sub
I added a little check to make sure we have an even number of pages and I + 1 in the pdf export command.
A few more user input checks might be necessary.