Open PDF, save DOCX bugs out after a few dozen documents and outputs garbled/corrupted files - vba

Question

I have a few thousand PDF files that I needs to convert to DOCX. I wrote the following macro:
Sub convertPDFtoDOCX()
'
' convertPDFtoDOCX Macro
'
'
Dim docDirectory As String
Dim pdfDirectory As String
Dim docPath As String
Dim doc As Document
docDirectory = "C:\Users\<USER>\DOCX\"
pdfDirectory = "C:\Users\<USER>\PDF\"
pdfFile = Dir(pdfDirectory & "*.*")
Do While pdfFile <> ""
docPath = docDirectory & pdfFile & ".docx"
Set doc = Documents.Open(FileName:=pdfDirectory & pdfFile)
ActiveDocument.SaveAs2 FileName:=docPath, FileFormat:=wdFormatXMLDocument
Documents.Close
pdfFile = Dir
Loop
End Sub
It works fine for the first few dozen documents, but then starts outputting "corrupted files", that aren't docx and can't be opened with a PDF viewer either. There is no error message when it starts bugging out. The problem doesn't come from the PDF files, since if I stop the macro and start it again on the same documents, they are correctly converted the second time.
"Corrupted" files looks like this:
%PDF-1.5
%µµµµ
1 0 obj
<</Type/Catalog/Pages 2 0 R/Lang(fr-FR) /StructTreeRoot 91 0 R/MarkInfo<</Marked true>>>>
endobj
2 0 obj
<</Type/Pages/Count 21/Kids[ 3 0 R 27 0 R 31 0 R 42 0 R 44 0 R 46 0 R 48 0 R 55 0 R 59 0 R 61 0 R 63 0 R 65 0 R 67 0 R 69 0 R 71 0 R 73 0 R 75 0 R 77 0 R 79 0 R 81 0 R 88 0 R] >>
endobj
3 0 obj
<</Type/Page/Parent 2 0 R/Resources<</Font<</F1 5 0 R/F2 9 0 R/F3 11 0 R/F4 16 0 R/F5 18 0 R/F6 20 0 R/F7 25 0 R>>/ExtGState<</GS7 7 0 R/GS8 8 0 R>>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<</Type/Group/S/Transparency/CS/DeviceRGB>>/Tabs/S/StructParents 0>>
endobj
4 0 obj
<</Filter/FlateDecode/Length 4428>>
stream
xœ­\Ën7Ýð?Ô.Ý ¨Ä7«‚ ¹%e4ð+²’Y$Yt¤¶£A,9RÛÈüÕ|Æ|ÆìÙäæ^²ÈzðQ-¦ È]U¼$//:<yØÞ¾__o«££Ã“ív}ýóæ¦úþðÅýv{ÿñÇë}Ú¾]¸½[ooïï
What causes the issue and how can I fix it?
I use Word 2016 on Windows 10.

Answer 1

I don't think you can fix the issue without a patch from Microsoft. Meanwhile, you can move your code to run outside Word and create a new Word.Application object for each iteration.