This looks like https://bugzilla.mozilla.org/show_bug.cgi?id=1672370 which we have a patch for. I'm hoping we will release a Firefox 82.0.1 with this fix (I don't make these decissions), but that will take at least a couple of days to get out.

In the meantime, one thing you could try experimenting with is turning on the new printing UI by opening the page `about:config`, typing in "print.tab_modal.enabled", and toggling that preference to `true`. You will then get the new printing user interface (not yet complete, but possibly(?) good enough for your purposes). We've had reports from some users that this new interface works for receipt printing with their receipt printers. I'd be very interested to hear back about whether it does or does not for you, and the details of what you tried and what worked/didn't.

It would also help us to know which printer models you're using, and which (if any) work with the new printing interface.

Note that in the new interface you can expand the "More settings" area to get a "Paper size" option where you can select the paper size. You may for now need to select the paper size each time you print. :-/ (Let us know if that's the case.)

Thanks for your answer but it was unfortunately not solved by setting the parameter "print.tab_modal.enabled" to true. I have already tested with different paper sizes but once the silent printing is enabled, it no longer prints the content of the receipt only the small ticket with the name of the print job.

An exmple model of printer is Star Micronics receipt Star TSP 100 & TSP650II

Can you clarify whether when you're turning silent printing off you also need to manually select the correct paper size **every** time you print, or whether with silent printing off it just works without needing to do that? It sounds like the latter since you didn't mention having to manually set the paper size each time, but if that's the case we're confused about why that would happen, and we would need to dig deeper.

Regarding a temporary workaround for you, it would be good to know what the prefs in `about:config` are set to in a working Firefox 81 (I guess these may vary for different printer models, unfortunately):

``` print_paper_height print_paper_id print_paper_name print_paper_size_unit print_paper_width ```

I think it's possible that if you turn off silent printing, do a successful print, then set the pref `print.always_print_silent` back to `true` and **also** set the pref `print.save_print_settings` to `false`, that will make subsequent silent prints use the correct settings and also stop those settings being reverted.

If that doesn't work then it may require setting the above five prefs manually to the correct values (obtained from Firefox 81 for the given printers) and setting `print.always_print_silent` back to `true` and **also** set the pref `print.save_print_settings` to `false`, all in one go.

Hello, I think we found the problem and also the solution in the about:config for the star TSP 654 printer. Changing the paper size solved the problem. The test is done on 2 computers, now we need to check if this is the solution for all computers.

That's great to hear. Can you clarify exactly what steps you take and settings (with values) you set on each computer to get things working for you?

You need change the paper size since the default paper size gives this problem. After changing that it works again.