Libreoffice cannot be started at runtime in php

I have installed LibreOffice version 6 at my 64 bit Windows 7 OS. If I try to convert .docx to .pdf from Command Prompt, it just works fine. But if I try to execute the command from laravel, it reports that the application cannot be started.

Laravel Code

$process = new Process('"C:\Program Files\LibreOffice\program\soffice.exe" --headless "- env:UserInstallation=file:///tmp/LibreOffice_Conversion_${USER}" -convert-to pdf --outdir D:\converted\ D:\acceptance.docx');


Error Message
image description

No idea if that helps, but your -env:UserInstallation URL seems incorrect for a Windows OS: it should start with “file:///C:/tmp…” or somesuch.

By the way, that is not version 6, that is version 6.3: both first version number parts are equally significant.