If you are seeing PDF File which cannot be processed and failing with below exception then it indicates that the PDF file is corrupt. Windows 10 2018-04-16T17:14:11,247 ERROR pool-4-thread-3 com.ephesoft.dcma.util.PDFUtil – Error in reading the file:<PATH> \0000_PV-Rech-1867010.pdf
com.itextpdf.text.exceptions.InvalidPdfException: PDF header signature not found.


Before the conversion process starts the PDF file has to be validated. The validation of PDF happens using Itext which does operations like page count and syntax check.
This PDF file is failing in this validation only and hence the PDF to TIFF conversion not starting.  This exception is due to missing header information in PDF file and seems that the PDF file is corrupt.

In this case customer need to verify the PDF file and check their PDF creation process.