The new PDFTron SDK HTML2PDF module has dependencies that may or may not be installed by default on a particular Linux distribution. These must be installed to convert HTML to PDF using Chromium. The missing dependencies can be found using the ldd command.
Here is an example checking the dependencies on Debian 10 (buster).
Ex.
ldd html2pdf_chromium.so | grep “not found”
libnss3.so => not found
libnssutil3.so => not found
libnspr4.so => not found
libexpat.so.1 => not found
In this case the libnss3 package is not installed by default.