There is a bug on file for this but it's still in the early stages of investigation, as you can see: [https://bugzilla.mozilla.org/show_bug.cgi?id=1089188 1089188 – Printing blank pages on Windows 10] I think someone with knowledge of Windows printing will need to step up and examine what has changed on the Windows print API side, or it could be a while before this gets addressed. If you are using Windows 10 as your main OS and Firefox as your main browser, as possible workaround is the Print pages to PDF extension: https://addons.mozilla.org/firefox/addon/print-pages-to-pdf/ - this does not use Firefox's print code, but extracts the page to an embedded Webkit-based renderer to create the PDF.