User Agent: Mozilla/5.0 (Windows NT 10.0; rv:75.0) Gecko/20100101 Firefox/75.0

Steps to reproduce:

Firefox 75.0 will not print on all NINE of my Windows 10 (32-bit) computers (Both Home and Pro). Printing will not work in either normal print or print preview.
All other printing form other applications and browsers works fine. Tried three different printers and Firefox 75.0 will NOT print to any of them from any machine.

Actual results:

I uninstalled Firefox 75.0 on one machine and reinstalled Firefox 74.01 and immediately could print again. I uninstalled FF 74.01 and installed Firefox 76beta4.
I could print in FF 76b4 but only from print preview.
I reinstalled the current build of Firefox 75.0 and again could not print at all.

Expected results:

To recap....
Current build Firefox 75.0 will NOT print at all on all nine of my Windows 10 (32-bit) computers. (Both Home and Pro).
Firefox 74.01 WILL print without issue.
Firefox 76.0 Beta 4 will print ONLY FROM Print Preview.
Again all machines are running Windows 10 32-BIT.

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

huh, is there any chance you could track down where this broke using mozregression?

Jonathan, are you aware of any windows-specific changes that could've landed in 75?

Sorry, Don't have time now for mozregression...

BUT...I did find a partial workaround...

I can now print from PRINT PREVIEW...

Before I could not but what I did was disable the PRINT PROGRESS DIALOG...

1. about:config
2. print. show_print_progress TOGGLE TO FALSE

I am now able to print from PRINT PREVIEW.
Normal PRINT still does not work...

It is DEFINITELY a FIREFOX 75.0 problem.

Resetting severity to default of --.

Can you clarify what specifically you mean by "cannot print"? (Where in the process do things fail, and how do they fail? e.g. a crash, a hang, a blank printed pages, an error dialog, or silent failure where we think we printed but no pages come out, or something else...?)

Also, just to help rule things out: are you able to print to PDF successfully? (As I recall, Windows 10 has a print-to-pdf option available by default -- does that work & only "real" printers are broken?)

Any additional info (and screenshots/photos as-appropriate) would be useful to help us understand what's going on. Thanks!

Meaning...When I hit PRINT....NOTHING happens thereafter. Nothing is sent to ANY Printer (Three different model printers).
As I stated above I found a work around by DISABLING PRINT PROGRESS DIALOG ...

about:config
print. show_print_progress TOGGLE TO FALSE

I am now able to print from PRINT PREVIEW.
Normal PRINT still does not work...

What I did find after implementing the work around is that I must first hit PRINT once...
It doesn't do anything...
Then I can hit PRINT PREVIEW and print successfully from there.

However after doing that I must restart Firefox as it is FROZEN at that point. (Cannot do anyting further).

STRESSING THIS AGAIN...This is the Windows Version of FIREFOX 75.0 32BIT on WINDOWS 10 32-BIT Systems.
It is the same on all NINE of my WIndows 10 32bit systems.

Firefox 75.0 for Linux prints fine on my one Linux system.

And yes....I can PRINT .PDF files no problem...I have Firefox set to open ACROBAT READER to open a .PDF file...From there I can print without issue.

(In reply to DaveI from comment #6)

Meaning...When I hit PRINT....NOTHING happens thereafter.

Sorry, further clarification would still be helpful. :)

(1) I assume you're opening the File menu and choosing "Print". Is that right? (Or are you doing Ctrl+P? Or opening Firefox's three-lines "hamburger menu" at the top right and clicking the "print" button in that menu? [note that this actually opens print-preview] Or clicking a "print" button on a website? or something else?)
(2) If you're doing File|Print [my best guess]: does that bring up a print dialog? (I'm guessing yes)
(3) Assuming "yes" so far: from there, I assume you choose a printer and you hit the "print" button on that dialog, and then what? Is that the part when nothing happens? (which I assume means, the dialog disappears and you're back to looking at a normal Firefox window, and nothing prints? Or something else?)

And yes....I can PRINT .PDF files no problem...I have Firefox set to open ACROBAT READER to open a .PDF file...From there I can print without issue.

To clarify, I wasn't asking if you "can print PDF files" -- I was asking if you can print to a PDF file. In Windows 10, if you can get the print dialog to show up (which I'm not entirely sure you can), then you should see "Microsoft PDF Printer" as one of the available printers, and that lets you choose a filename and it will generate a PDF file for you, doing a virtual "print" operation. (I ask about this because it helps rule out certain classes of issues -- some problems happen only with remote/real printers, whereas other problems happen even with virtual printers including this Microsoft PDF Printer.)

1. Yes. I am using File Menu and "Print"
2. Yes it brings up the print dialog
3. I choose a printer and hit PRINT...Then NOTHING...No Printer Icon in the Tray either.
4. Regarding PDF Printing to the Microsoft PDF Printer...
   I selected that and it also went to nothing...No prompt to name a file and select a location.

However as I previously wrote. At that point....I can choose FILE MENU /PRINT PREVIEW and print from
there. However after that Firefox will be froze (Unreponsive) and I have to close and reopen it.

BTW, I was in my Garage when you wrote and that computer would print normally (32bit Windows/Firefox 75.0)...
However all the others I had tested previously had the problem...I went into the house to confirm the problem still exists.

All systems are Windows 10 1909 32bit (Home or Pro). Firefox 75.0 32bit.
All updates are in place from Windows Update.

Hi Davel, are you able to download a build of Firefox 76 Beta? Starting in Firefox 76 we will track printing errors through telemetry. Please download Firefox 76 and see if you are still having issues printing. If so, then can you go to about:telemetry, click on Scalars, and search for "printing"? Please let us know what errors are listed for you under the "printing.error" scalar.

So I imaged my primary system (Which is one of the systems with the printing problem)...
I imaged as I do not want to remain on the Beta Channel and Don't want to have to reinstall Firefox and restore settings, customizations, etc.

I then downloaded the Firefox Beta Installer and ran and installed the latest BETA as requested. (It's now currently on Firefox 76.0b8)

I then tested printing with the BETA verison. It is exactly the same situation as it is under Firefox 75.0.

I first tried normal printing (FileMenu/Print)....Nothing...
I rebooted and then tried printing from PrintPreview....Nothing...
I rebooted and then tried what worked under Firefox 75.0... FileMenu/Print...Nothing....Then immediately PRINT PREVIEW/PRINT...And then it prints.
But as it did under Firefox 75.0 the Browser after printing becomes unresponsive (Cannot browse to any other sites) and requires it to be closed and reopened again.

As requested I opened about:telemetry, clicked on Scalars and searched for "printing"...

Here is all that is listed...I don't see any errors...Just a fingerprint setting I have set to blocking...

parent process
contentblocking.fingerprinting_blocking_enabled 	true 

I have to do a bunch of work but will be available on and off today...
I will leave this BETA version installed today incase you want me to do anything else...
I will restore the computer image back to the original with FF 75.0 after today...Thanks.

Thank you for doing that and I'm sorry that we're not recording this printing failure as I hoped. Would you mind testing using mozregression to find exactly what changed that broke printing for you? https://mozilla.github.io/mozregression/ has information about how to download and run Mozregression. The tool will download different builds of Firefox for you to try, and after about 10 different builds it should be able to tell the exact change which caused printing to stop working for you. This would be of tremendous help to us.

I ran mozregression as requested on my primary machine...

The end result in the log was this...

2020-05-02T20:48:57.074000: DEBUG : Found commit message:
Bug 1552966. Convert the printing code to stop using DocShellTree* classes. r=farre

Differential Revision: https://phabricator.services.mozilla.com/D56830

2020-05-02T20:48:57.074000: DEBUG : Did not find a branch, checking all integration branches
2020-05-02T20:48:57.074000: INFO : The bisection is done.
2020-05-02T20:48:57.074000: INFO : Stopped

I tested from known good build 74
to known bad build 75

It tested 12 builds and 5 builds tested good (Was able to print as normally (File Menu/Print)

The Bug 1552966. Convert the printing code to stop using DocShellTree* classes. r=farre
I believe I saw a dev request for this to be implemented some time back (In a Mozilla forum somewhere)...
It appears that this is what is causing my printing issues on multiple WINDOWS 10 32bit PCs.

I see I am not the only one...

https://bugzilla.mozilla.org/show_bug.cgi?id=1620314

Fwiw, not sure it's the culprit, but this is not right / equivalent to the older code.

You're in the chrome process, but the outer window for the top level browsing context lives in the child. What the older code was doing was getting the XUL window, which is different, I think...

Thanks for your patience and help here, Davel. With all the settings as they were when the problem occurs, can you open the page "about:support", click "Copy text to clipboard", save the results to a file and attach them here?

Attached file about:support info

(In reply to Jonathan Watt [:jwatt] from comment #16)

Thanks for your patience and help here, Davel. With all the settings as they were when the problem occurs, can you open the page "about:support", click "Copy text to clipboard", save the results to a file and attach them here?

As requested. I am now on Firefox 76.01 stable but the settings have not changed and the problem remains as it did in Firefox 75.0.
The problem began in FF 75.0. Settings have not changed.

Thank you.

One thing I should point out is that you have a space character in "print. show_print_progress" that will mean that pref has no affect. Can you check whether removing that space allows you to print again?

As requested...I toggled it from FALSE to TRUE... Closed FF and reopened and attempted printing...Problem remains.
BTW I edited that setting when this problem began in FF 75 trying to get the printing working. Have you looked at the
DOCSHELL issue. I remember seeing a DEV request that be removed some time back. Is there a something that could have
been broken by that being removed?

I found the PROBLEM...
Something that was changed starting in FF75 has caused the PRINTING PROBLEM
if you have ELECTROLYSIS (E10s) Disabled.
I have had this disabled at first in the settings. And then when it was mandated
and could no longer be disabled in the settings I disabled it in the ENVIRONMENT
VARIABLE

Variable Name: MOZ_FORCE_DISABLE_E10S
Variable Value: 1

I took that out that just now and rebooted and immediately was able to print from FF76.01.

The reason I had been running FF with E10s disabled for the past few years (With no printing problems
prior to FF 75) was that clicking on Email Ads (From my Email client) would result in a WHITE PAGE in FF.
Bypassing E10s cured that issue. However I have just tried several ADs from my Email Client and it went
to the AD in FF correctly. So I will reenable E10s on all of my computers (Even though it's a resource hog).
Hope this helps in some way. Thanks.

(In reply to DaveI from comment #20)

As requested...I toggled it from FALSE to TRUE... Closed FF and reopened and attempted printing...Problem remains.

I didn't mention toggling it - I mentioned that the name of the pref is wrong in your settings. The name in your settings is "print. show_print_progress" (has a space character in there, after the "."), whereas the correct name is "print.show_print_progress" (no space). So as it is, toggling the pref wouldn't have any affect for you until you remove the space character.

(In reply to DaveI from comment #21)

I found the PROBLEM...

Variable Name: MOZ_FORCE_DISABLE_E10S
Variable Value: 1

Argh! For some reason I thought it was impossible to disable e10s without a custom build since we removed browser.tabs.remote.autostart in Firefox 68.

Hope this helps in some way. Thanks.

It's very helpful, thank you for figuring that out and all your patience!

And just to confirm the resolution...I enabled E10s on all NINE of the Windows 10 32bit systems
with FF 76.01 and ALL NINE are now printing normally.

Thunderbird has a strong printing user community, for business and other reasons. I'm unsure about Firefox.
Is this bug prioritized for version 78 - which is the next big Thunderbird release and the next Firefox ESR?

I've put up a partial backout patch in bug 1639816 and plan to request uplift to 78. Can you confirm that that patch fixes things for Thunderbird?

looking good, per bug 1639816 comment 9.
Thanks for proactively looking at this

Looks like that uplift-to-beta has now happened (in https://bugzilla.mozilla.org/show_bug.cgi?id=1639816#c11 ).

Wayne, could you confirm that Thunderbird 78 beta is looking OK on this now? Or is there more that needs to be done here for 78?

I think this was picked up in beta 2, and we subsequently adjusted.
Walt, do you agree printing is back to normal?

(In reply to Wayne Mery (:wsmwk) from comment #29)

I think this was picked up in beta 2, and we subsequently adjusted.
Walt, do you agree printing is back to normal?

Just tested email printing from File > Print and File > Print Preview using 78.0b3 on Windows 10 and Ubuntu 18.04.4 LTS successfully.

Also tested calendar printing and no problems there.

Thanks for confirming.