hi hanos, could you try the following and report back if this can turn the browser functional again?:

• navigate to your profile folder: Profiles - Where Firefox stores your bookmarks, passwords and other user data
• while no firefox processes are running, right-click and edit the file prefs.js
• add the following line into the file and save it: user_pref("security.sandbox.content.level", 0);

hey @philipp,

i tried what you said, but with no success. i tried it both in Windows Safe Mode and the normal one too. Strangely, after opening the browser and closing it, in that js file, the line i added is removed. i know that it says if there is any active Firefox processes it'll do so, but still though it'd help. I made sure Firefox is not active using the Task Manager and the file is not changed until AFTER i open the browser once

thanks for testing it. in the past we've seen the exact same issues from users who had set firefox to run in compatibility mode (bug 1614885) or also with some external software like gdata (bug 1610790) - given that in windows safe mode it's working for you, some sort of external interference would be a likely explanation too. do you know if you're having an unusual security configuration or have software that would somehow interfere or try to sandbox firefox?

otherwise what would also help is if you could use the tool at https://mozilla.github.io/mozregression/install.html to dig up the exact regression range of when this problem started appearing in mozilla's development builds, so we can ping the right people about this problem. please let me know if you need any help with that.

Huh that's weird.. I have been having this problem since last night only. And I don't think anything's interfering with Firefox.. Anyway let me look over once more.

Yeah, I would love some help. What do I do with tool?

firefox 75 was released in the past days, so i guess that's what triggered the problem.

after you've downloaded and installed (might have to skip some warning messages, because the installer isn't digitally signed) the tool from https://github.com/mozilla/mozregression/releases/latest you should be able to launch it from the start menu.

• go to file > run a new bisection
• in the "basic configuration" & "profile selection" dialogues you can just click on next
• in the "build selection" dialog set last known good build to "release" and "74" and click on finish.
• now the tool will start downloading and opening builds - see if you can reproduce the problem in each and then go back to mozregression to mark them as good or bad.
• this will continue until you've narrowed down the range to a single build or changeset - at the end the tool should provide some DEBUG information in the log section and/or a pushlog url in the bisection section which are of interest to us :))

I'm also having this problem on my Acer Swift laptop. If I install Firefox 74, firefox runs with no issues at all. After upgrading to 75, the behavior persists. I've already tried deleting all mozilla folders on multiple locations, (appdata/programdata/programs folders) after uninstall, then perform an install from a freshly downloaded Firefox Installer.

No joy for firefox still.

I'm typing this on another browser as I can no longer use Firefox version 75.

Thank you for your help.

Attached is the snapshot of the log from Mozregression-gui:

@HACKERSOFT: thanks, but this was just the first step - depending on if the build could load pages or not, please click on "good" or "bad" in the window and these steps will continue until you have narrowed down the regressor.

I did it again and everything was bad until the end of the run-time.

I noticed that my desktop computer is now having the same problem, I just upgraded it yesterday, and firefox is now giving the same behavior.

Here's the last screenshot of the mozregression-gui tool log today.

Any help?

is there any change when you start with an earlier release in the "last known good build" field, like 72?

also can you think of any particular security/sandboxing software or other configuration that would be the same on both of your affected devices (it would have to be fairly rare in general since so far we only have a handful of such reports after the 75 update)?

thank you

As I've previously mentioned, Firefox 74 works fine with no problem.

It seems like now, with all of our computers updated to Firefox 75, the issues are the same. It's just loaded without any rendered pages and the only way to close it is via task manager or CTRL + Shift + Q.

Thank you for looking into this issue.

We've been using Firefox and love it more than other browsers but it seems like this upgrade issues may force us to use other alternatives.

HACKERSOFT said

As I've previously mentioned, Firefox 74 works fine with no problem.

yes, i understand that. but for testing purposes i'd ask to try with a earlier last known good release in mozregression anyway. because this tool doesn't test firefox release builds, but nightly builds that are in development that may contain new features/changes that do not get shipped to release (or just in a later version).

It seems like now, with all of our computers updated to Firefox 75, the issues are the same. It's just loaded without any rendered pages and the only way to close it is via task manager or CTRL + Shift + Q. Thank you for looking into this issue.

if this is in a particular corporate environment it would be even more important to know what kind of security software or settings are in place. the cause of the problem needs to be somewhat understood to work out a fix quickly. we had seen issues with the same symptoms in firefox 73 for users of a particular version of gdata security software for example: https://bugzilla.mozilla.org/show_bug.cgi?id=1610790

I've tried updating Firefox on my personal laptop first and it is using Windows Security (no other antivirus/firewall installed).

I'm on Windows build 1909 (OS Build 18363.752) if it would matter as some of our computers are still on build 1903 and some 1809.

Other than that, all installed software run perfectly except for Firefox when updated to version 75.

Hi! On our computers I think I've found out the cause of the problem.

It seems that Firefox is conflicting with NetSupport School running in the background.

If I terminate NetSupport School background processes, Firefox 75 loads with no problem.

I wonder what is triggering the issue and conflict with NSS software?

Anyway to figure out what's causing the issue?

thank you, i could reproduce that and filed a bug report: https://bugzilla.mozilla.org/show_bug.cgi?id=1629361

Just an update from NetSupport, they are now working on the issue and will help figure out what is causing the problem.

Meanwhile, a temporary fix was provided by them as instructed below:

For 32bit machines- Browse to the C:\Program Files\NetSupport\NetSupport School directory. Rename the pluginsoftwaremodule.dll to pluginsoftwaremodule.bak.

For 64bit machines- Browse to the C:\Program Files (x86)\NetSupport\NetSupport School directory.

Rename the pluginSoftwareModule64.dll to pluginSoftwareModule64.bak.

Reboot the machine when complete.

After doing that, Firefox should run with no problem.

hi again, 76.0b5 was just released and has a potential fix for this - could you try it?: https://www.mozilla.org/firefox/all/#product-desktop-beta

on the first start it will likely exhibit the same problem, but after you force-close it once and restart the beta build, firefox should hopefully be back in working order.

Yes, verified that it worked after force quitting once.

Update from NetSupport.

They now have an available and working patch as well and will be released soon as Version 14.00.0004

I applied the patch they've sent me and everything is working as it should even without installing Firefox 76.0b5.

Thank you everyone for working on it!