Some PDF files are marked by the person who produced them so that their contents are not allowed to be copied or extracted. This means that you cannot extract any data from them.

Adobe Systems Inc®, the company that created and maintains the PDF format, requires all applications that use this format to honor this special limitation.

When you open such a PDF file, PDF2XL will let you know this by displaying the following notification:

Text cannot be extracted from this PDF file. Do you wish to open it anyway?

If you click on Yes, the file will be opened but you will not be able to extract any data from it. Neither by converting to Excel, Word and the clipboard, nor by selecting and copying text.

More information about this feature of Adobe Acrobat and PDF files is available on the Adobe website