As odoo has got sticked to old version of wkhtmltopdf and new os are not having wkhtmltopdf version 0.12.1 build so is possible to anyhow fix the issue in new OS like debian 9.
Anyone who can help for same.
Odoo is the world's easiest all-in-one management software.
It includes hundreds of business apps:
uninstall the one comes with debian9 and download earlier version and install it somewhere under /opt/ maybe and link it /usr/bin/wkhtmlpdf ...