Problem:
An error occurred when running the "makesearchable" command line.

Solution:

Downloading and installing the Win2PDF Desktop with OCR setup program should resolve the problem.  It can be downloaded from:

https://www.win2pdf.com/download/download-win2pdf-ocr.html

Also, the "makesearchable" command requires that you specify the full path to the win2pdfd.exe executable.  In most cases, this would be:

c:\windows\system32\spool\drivers\x64\3\win2pdfd.exe makesearchable input.pdf searchable.pdf