I assume this is caused by something in that specific PDF.

If it is a publicly available document, you could share the URL here or, even better, report the bug over on the Github Issues list at https://github.com/mozilla/pdf.js/issues

If it's confidential, I'm not sure where to look for leads. Firefox's Browser Console (Ctrl+Shift+J) collects error messages from centralized functions like printing, so maybe you'll see something there at the point of failure?

error printing a pdf thru firefox. it prints with edge. i am trying to report the problem. it fails at 7 of 33 pages and the printer que shows error. firefox latest version Military CF31 MK5 laptop Edition Windows 10 Pro Version 22H2 Installed on ‎5/‎28/‎2023 OS Build 19045.6466 Canon D570 printer Will print with either MS Edge or any pdf reader I tried...busy, cannot continue this It needs looking at

Sounds like a classic Firefox + printer driver hiccup. I’ve seen this before where Firefox’s built-in PDF renderer just chokes partway through a bigger document, even though everything else prints fine. Easiest workaround is to disable Firefox’s internal PDF viewer and force it to open PDFs in an external reader (like Adobe) or just keep printing via Edge for now. Also worth checking for a newer Canon D570 driver or switching the printer to a basic PCL/PS driver, that alone fixes a lot of these mid-job queue errors. Definitely feels like a Firefox bug rather than your laptop or printer.