We're running Windows 10 Enterprise build 19045. Please also note, we also attempted version 138.0.1 and later versions 137.0.1 and 136.0.3. The only versions that work are versions 62.0 and 73.0.1 x64 however these versions are unable to get updated to v138.

Do you have any extensions installed?

No, there aren't any extensions installed.

One other noteworthy item, the update to v138.0 successfully worked on some and NOT getting "Gah ..." errors. Unfortunately we have over 100 computers running various versions of Firefox and not sure the original version or the version prior to the update and/or if updating to v138 has a pre-req version requirement. Is there a way to find the previous version of Firefox prior to it being updated to 138.0 after Firefox has already been updated?

So for in trying to rule out the different versions, we've already tested the update from Firefox version 62, 72.0.1, and 73.0.1 by installing this older version and attempting to update it with version 136.0.1, 137.0.1, 138.0, and 138.0.1, all resulting with the same error. We are manually applying the update and also tried using Ivanti Secure Controls in an attempt to automate the process.

Any other thoughts? Thank you.

We do have a tool that can help us track down when a crash started.

https://mozilla.github.io/mozregression/

You could use this to see if it could tell us when things broke.

In looking into this a little more, other than changing to Troubleshooting Mode, another workaround is to rename the file Firefox.exe to something else like Firefox1.exe and then use/launch Firefox1.exe. This appear to fix the issue however unsure of any ramifications with renaming the Firefox.exe may have.

We suspect there's Firewall or IPS preventing the use of Firefox.exe which was somewhat indirectly proven by renaming the Firefox.exe file to something else.

That's an interesting observation.

Renaming the EXE should have no ramifications. We query the name of the EXE to use it, we don't hardcode the EXE name.

I'm curious, if you go to about:crashes, do you see the crashes there?

I'm wondering if we can look at some of the crash reports.

There is nothing showing in about:crashes.

Can you turn on crash reporting in preferences and then recreate? That should send a crash report.

Turning on or enabling "Automatically send crash reports" under the section "Firefox Data Collection and Use", does not create a crash report after the crash. Also enabling "Troubleshoot mode" appears to temporarily resolve the crash and/or does not generate a crash report.

Any other thoughts? Thanks.

> Turning on or enabling "Automatically send crash reports" under the section "Firefox Data Collection and Use", does not create a crash report after the crash.

That's concerning. I asked, and it should...

> Also enabling "Troubleshoot mode" appears to temporarily resolve the crash and/or does not generate a crash report.

This implies that it is either an addon or a preference that is set.

Can you try disabling addons one at a time?

There are no custom or user preferences or addon set or installed. Firefox has the default out-of-the-box settings. Here are things attempted: 1) initially the PC had Firefox version 6.2. The PC was updated it to version 138.0 using Ivanti and after the update the Error started.

2) Firefox was uninstalled on the PC and version 6.2 installed and manually updated Firefox to version 138.0 and/or 138.0.3 (not Ivanti), resulting with a successful installation but the same error returned when attempting to go to a website.

3) Firefox was uninstalled on the PC from the 2nd attempt, and a reinstall of Firefox version 138.0.3 was successful but the same error happened when attempting to go to a website.

For all installs, there were no changes to preferences or addons. However, the fact that the Firefox.exe file can be renamed to Firefox1.exe and successfully launch Firefox1.exe and connect to a website, tells us there's something preventing the execution of Firefox.exe, perhaps a firewall or IPS or GPO. We're exploring these possibilities now to try to address the issue.

One really strange thing with this issue is, so far we can successfully install older versions of Firefox like 6.2. and 7.3 and connect to website without problems. However, if/when newer Firefox versions like 136.0.1, 137.0.1, or 138.0.3 are installed, the error happens and unable to connect to website. We've attempted installing using the .exe and .msi both resulting with the same error.

So the theory that a Firewall/IPS or GPO preventing Firefox.exe from launching does not seem to be reasonable since Firefox 6.2 or 7.3 works.

Is there some new extension or addon with the newer Firefox versions on Windows 10?

Do you really mean Firefox 6.2? Those are many years old :)

So that's where mozregression would help here:

https://mozilla.github.io/mozregression/

Yes, unfortunately we've inherited many computers that have not been maintained running old versions like 6.2 and 7.3. Also, the PC are on a closed network, with no public internet connection including a very lengthy approval process for new software like mozregression. We'll start the process to getting mozregression but is there another way to see the possible cause or error like using wireshark?

Is there pre-requisite for old versions like 6.2 or 7.3 to be upgraded to version 138 or new versions?

> Is there pre-requisite for old versions like 6.2 or 7.3 to be upgraded to version 138 or new versions?

If they work for you, there's no reason to upgrade, especially on closed systems.

Can you try doing a few major versions to see if the problem started at a specific time?

I just wish the crashes were bring reported. That would help.

Still nothing in about:crashes?

Unfortunately, still nothing in crash reports or about:crashes

Also, unfortunately the computers are appearing on Cyber Security reports showing vulnerabilities in the old versions of Firefox, hence the reason we're trying to update to a newer version.

Can you reach out to me at mkaply at mozilla.com?

I'm wondering if there's a chance we can video conference or do something else to help figure this out.

Mike, Thanks for your help so far. However, as mentioned the computers are in a closed network and unfortunately doing a video conference is not an option or a luxury we have in the office.

I think we may have found a fix. It seems for the Firefox.exe file, there's a Property setting for "Run this Program in Compatibility mode for Windows 8". If the checkbox is selected for this setting and the browser cache is cleared, the browser tab crashing issue goes away. This setting is also per user, which means each person that uses the computer, this setting needs to be set. Is there a way to set this setting for all users?

It is also interesting that this Compatibility setting is not needed for some computers that were successfully updated to Firefox version 138. We're trying to find the differences between the computers but so far we've not found any differences and is a mystery/baffling.

Thanks again.

Is there something during or after the installation of Firefox to set the Property value to "Run program in Compatible mode for Windows 8", perhaps in a Firefox Config File, ideally for all users?

Appreciate any feedback.