Bugzilla

The landed version of this patch uses the system default printer, if one is set. It does not further fall back to trying to get an available printer list using the nsIPrinterList as the original version of the patch did. That's because it seemed way too risky to uplift that to Beta, given that it requires making a bunch of code async, and the APIs to get the printer list and default settings from a printer have very variable delays according to our telemetry, for ~1% of users taking over (potentially way over) 10 seconds.

This patch fixed the issue for me on Window 10 and macOS 10.15.7. It did not fix things on Ubuntu 20.04. Again, the differences are whether a system default printer is set or not. It's possible the patch will not fix the issue for Windows 7 users (I don't know, yet), and it's possible that it will not fix the issue for macOS users who have never printed before using **any** app on their computer. However, the issue is only present for users using the old UI, who have never printed using Firefox before, and who are using Print Preview or the Page Settings dialog. (Our telemetry says that only around 7% of prints are made via print preview, and presumably a similarly small number of prints involve the Print Settings dialog.) That should be a relatively small subset of users affected (albeit mostly new users, the ones we're trying to retain), and the patch on this bug should make it a much smaller subset of users. As for the rest, I think we may have to live with the regression until we switch to the new print UI.

The landed version of this patch uses the system default printer, if one is set. It does not further fall back to trying to get an available printer list using the nsIPrinterList as the original version of the patch did. That's because it seemed way too risky to uplift that to Beta, given that it requires making a bunch of code async, and the APIs to get the printer list and default settings from a printer have very variable delays according to our telemetry, for ~1% of users taking over (potentially way over) 10 seconds.

This patch fixed the issue for me on Window 10 and macOS 10.15.7. It did not fix things on Ubuntu 20.04. Again, the differences are whether a system default printer is set or not. It's possible the patch will not fix the issue for Windows 7 users (I don't know, yet), and it's possible that it will not fix the issue for macOS users who have never printed before using **any** app on their computer. However, the issue is only present for users using the old UI, who have never printed using Firefox before, and who are using Print Preview or the Page Settings dialog. (Our telemetry says that only around 7% of prints are made via print preview, and presumably a similarly small number of prints involve the Print Settings dialog.) That should be a relatively small subset of users affected (albeit mostly new users, the ones we're trying to retain), and the patch on this bug should significantly further reduce that subset of users given most of them are on Windows. As for the rest, I think we may have to live with the regression until we switch to the new print UI.