After upgrading 6.3.2 (Framework 2) to 6.7.1 (Framework 4+) we discovered a change in behaviour of the PDFNET component.
During conversion of a file from DOCX to PDF using convert.topdf(), the conversion routine is now visibly opening up WORD and printing to PDF.
Through experimentation we discovered that the calling convert.topdf() with a file name in lowercase is silent, whereas calling in uppercase causes WORD to verbosely open and print.
It doesn’t matter whether the actual physical file is document.docx or DOCUMENT.DOCX, it is the argument name you use in the routine that makes the difference.
In our system we map the real filename to the argument and all our files end in DOCX, not docx, which is now (not in 6.3.2) causing WORD to show and print.
Lowercasing our variable name when calling convert.topdf() is a workaround for us but this, as a change in behaviour from 6.3.2, should really be made consistent.