PDF header not found. The file is not a valid PDF document when use dochub tools


PDFTron DocPub utility 9.4280734.

Product Version:

PDFTron DocPub utility 9.4280734.
Copyright (c) 2001-2022 PDFTron Systems Incorporated, www.pdftron.com.

You are running a DEMO version of DocPub.
In the demo version, all converted pages will be stamped with a demo stamp.

Please give a brief summary of your issue:
(Think of this as an email subject)

An error message occur , when use dochub convert 0_.doc(this file is really doc file).

D:\test>.\docpub\docpub.exe .\zhihao\0_.doc
Unsupported format. The file can not be converted.
Error: An error occurred while converting the file.
Detailed error:
         Message: PDF header not found. The file is not a valid PDF document.
         Conditional expression: false
         Version      : 9.4.2-a2633dd18a
         Platform     : Windows
         Architecture : AMD64
         Filename     : Parser.cpp
         Function     : trn::SDF::Parser::SkipHeader
         Linenumber   : 1165

Please describe your issue and provide steps to reproduce it:
(The more descriptive your answer, the faster we are able to help you)

just convert on documents .

Please provide a link to a minimal sample where the issue is reproducible:

The proper command would be the following.

docpub --format pdf 0_.doc