Recap: The reason we were trying to cause it to crash is that the problem hasn't recurred in over a week and I was getting tired of waiting for it. We crashed it but we couldn't reproduce the downgrade.

Breaking news: It just crashed for the first time in a week. This time the behavior was different.

Before, it gave a separate dialog offering to restart. This time, it was an embedded page.

And this time, it created a crash report which it didn't before. bp-cf559e8f-d476-4ba7-b6a8-e25682161118

Not surprisingly, it did not roll back. Upgrading now to 50.

That was apparently a crash because Firefox ran out of memory again. That may be almost expected in some situations.

Does it look like the downgrading issue has disappeared ? Or maybe we need to wait until the next upgrade is released.

> That was apparently a crash because Firefox ran out of memory again. I watched dozens of news videos in a row and then it crashed. This is a different profile than any of the other incidents. Does the browser properly release memory after the video is over?

> Does it look like the downgrading issue has disappeared ? It is hard to prove a negative, but it hasn't come back since I did the full re-install well over a week ago.

bwhite said

> That was apparently a crash because Firefox ran out of memory again. I watched dozens of news videos in a row and then it crashed. This is a different profile than any of the other incidents. Does the browser properly release memory after the video is over?

You can check that and probably if necessary force Firefox to do so by using about:memory. If you are watching a lot of videos one after another and memory is not being released then it is sure to cause problems and crashes.

If you are having problems is it with streaming video - in which case what site are you using? _{or is it downloaded videos -probably unlikely you would then play them in Firefox unless you have bandwidth issues.}

There is also a relatively new built in tool storage inspector. That may help, but I have not tried using it or even got round to studying its features.

Sorry to ask again, but did you run any scan yet?

I may be wrong with my theory, but avoiding crashes and hoping for the best would not be my primary goal.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista if you don't already have one. Windows 8/10 have antivirus protection built-in.

Note there is a potentially similar issue reported:

• Firefox 50 trying to 'update' to previous version 49.0.2 /questions/1147745

That however involves different versions and is a Mac user.

It's back.

All tabs slowed down to where they were taking 2 minutes to update each. Another browser pulled up the pages immediately.

This dialog came up https://www.dropbox.com/s/mtuq8361l2lxkzy/Firefox_Stopped.png?dl=0

CPU usage was at 0%. Memory usage was the lowest I've ever seen it at 8.7 MB. Possibly swapped out.

One of the previous comments was that if I waited, FF would create a crash report. I waited 20 minutes, but it never reset on its own. It did not create a crash report.

It did roll back. https://www.dropbox.com/s/09yfhjgkjukmrgw/FireFoxRollback.png?dl=0

Hope that helps, Brad.

BTW, I had upgraded to 50.

I should have saved off the folder before I re-upgraded. Thought of that too late. Now back up to 50.0.1.

I'll run a Windows Defender full scan tonight. Any other scanner I should run?

I suggest you scan with all theones listed in

• Troubleshoot Firefox issues caused by malware

Sorry to say but I have asked if you scanned your system twice before. Additionally, a number of given questions are unanswered that you might or should be able to answer now, such as

• What process was active before the crash? (You should check occasionally even when nothing seems wrong - note the version numer AND process / file location - is it still the official one?)
• What process was active right after the crash, before restarting Firefox? (Sidenote: we call it a crash, but technically it isn’t - a hang may be the better word.)
• (+) What process(es) was/were active during the Firefox has stopped working dialog? (= What shows the dialog?)
• Were there any XML files and update files staged? (Probably not)

Plus

• Did you check the shortcut / menu entry prior to restarting Firefox?
• Did you have a look at some Windows system and application logs? Application hangs and crashes should be logged and also show process info.

A Firefox memory use of 8MB could be just as dramatically low as unbelievable and suspicious altogether. Process=?? With regard to generating a crash report: the more stable Firefox has become in terms of not crashing, the better it has become in hanging, hence not generating crash reports in 20 minutes is not uncommon in my experience, simply because it’s a hang.

In order to find what goes wrong, you just need to verify what happened and use the info available. No-one can find culprits just by looking at a browser’s behavior (unless it’s a very common issue) - logs are your friend, as well as active monitoring.

Another thought is, I think usually Firefox should come up with a "Firefox is not responding" error message - the "<name> has stopped working" error is a general Windows message and may occur for other applications as well. Avast is one piece of software able to cause the error. The error can also point to malware - have a look at all the suspicous programs listed in that article’s Step 1. Also, your error dialog displays a small Firefox icon in the top left with a green check mark. I’m not sure if that’s normal for Windows 10, but just wondering.

I don’t think antivirus or security products were mentioned here either. Perhaps you have some installed that are able to do some "system restore" for program files, or just Windows itself? And if you happen to know if you ever installed Firefox 45.0.1 manually, that would be great (and if so, find + scan its installer on disk, but you already scanned the system for older installers.) As said, any listing of a 45.0.1 upgrade in Firefox’s Update History Log, if it still exists, especially the first one ever? And do you recall ever installing a 32-bit or 64-bit version instead that doesn’t make sense compared to the 32-bit version seemingly getting restored? (Not sure, you need to check the version as soon as you see it, or by viewing its file properties - Firefox 43 was the first version to support 64-bit.)

My thoughts have not changed - something could cause Firefox to crash and replace the program files by a hijacked version either after or before the hang. If you change your system time to a week ahead, the next crash may be triggered sooner. Unfortunately that would make the system (or at least Firefox) unusable.

John99 said

I suggest you scan with all theones listed in

• Troubleshoot Firefox issues caused by malware

I scanned with Windows Defender last night. No issues. Scanning with the MS Safety Scanner now. Two others scheduled to go tonight.

Thanks for the list.

Tonnes said

Sorry to say but I have asked if you scanned your system twice before.

Scanned last night, scanning now, scanning again tonight. UPDATE: second scan finished. No hits.

Additionally, a number of given questions are unanswered that you might or should be able to answer now, such as

• What process was active before the crash? (You should check occasionally even when nothing seems wrong - note the version numer AND process / file location - is it still the official one?)

50.0

• What process was active right after the crash, before restarting Firefox?
• (+) What process(es) was/were active during the Firefox has stopped working dialog? (= What shows the dialog?)

Didn't check. I didn't have ProcessExplorer installed, so I didn't have as good a view into what applications are actually running. Fixed.

(Sidenote: we call it a crash, but technically it isn’t - a hang may be the better word.)

Correct.

• Were there any XML files and update files staged? (Probably not)

Not that I see.

Plus

• Did you check the shortcut / menu entry prior to restarting Firefox?

It is not a shortcut per se, but an entry in the Most Used list on the start menu. It starts the exe in C:\Program Files (x86)\Mozilla Firefox

• Did you have a look at some Windows system and application logs? Application hangs and crashes should be logged and also show process info.

Nothing shows up in eventvwr.

A Firefox memory use of 8MB could be just as dramatically low as unbelievable and suspicious altogether.

I generally don't trust TaskManager's results for memory used, but when I've checked it has consistently been showing between 100 and 200 MB. So 8MB seemed unusually low. ProcessExplorer installed now, so we'll have a better view going forward.

Process=?? With regard to generating a crash report: the more stable Firefox has become in terms of not crashing, the better it has become in hanging, hence not generating crash reports in 20 minutes is not uncommon in my experience, simply because it’s a hang.

ok.

In order to find what goes wrong, you just need to verify what happened and use the info available. No-one can find culprits just by looking at a browser’s behavior (unless it’s a very common issue) - logs are your friend, as well as active monitoring.

It doesn't seem to be logging anything.

Another thought is, I think usually Firefox should come up with a "Firefox is not responding" error message - the "<name> has stopped working" error is a general Windows message and may occur for other applications as well.

I agree that it should, but I'm not seeing it.

Also, your error dialog displays a small Firefox icon in the top left with a green check mark. I’m not sure if that’s normal for Windows 10, but just wondering.

I think you were right that this is not a FF dialog. It has a FF icon on the form but the icon with the check in the title bar is something else, like windows defender. I have that come up when Visual Studio hangs, so I can check.

I don’t think antivirus or security products were mentioned here either. Perhaps you have some installed that are able to do some "system restore" for program files, or just Windows itself?

I'll ask around.

And if you happen to know if you ever installed Firefox 45.0.1 manually, that would be great (and if so, find + scan its installer on disk, but you already scanned the system for older installers.)

No installer. I upgrade whenever it suggests, so I'm guessing that I did install 45.0.1.

As said, any listing of a 45.0.1 upgrade in Firefox’s Update History Log, if it still exists, especially the first one ever?

I didn't save a backup the first time I did a complete re-install. The current version only shows the upgrades, 50.0, 47.0.1, 50.0.1, since the last complete reinstall. The copies I do have saved do not show any upgrades.

And do you recall ever installing a 32-bit or 64-bit version instead that doesn’t make sense compared to the 32-bit version seemingly getting restored? (Not sure, you need to check the version as soon as you see it, or by viewing its file properties - Firefox 43 was the first version to support 64-bit.)

I was running 32 bit. Now upgraded to 64. Program Files path changed. We'll see if it happens again.

My thoughts have not changed - something could cause Firefox to crash and replace the program files by a hijacked version either after or before the hang. If you change your system time to a week ahead, the next crash may be triggered sooner. Unfortunately that would make the system (or at least Firefox) unusable.

That doesn't resonate. It was happening multiple times a day. Then 10 days ago we deleted the folder and reinstalled. This is the first occurance since then. Doesn't seem time based.

Thanks for the help and suggestions. Brad.

ProcessExplorer shows two Firefox processes. The first starts the second.

First is

   "C:\Program Files\Mozilla Firefox\firefox.exe"

Second is

   "C:\Program Files\Mozilla Firefox\firefox.exe" -contentproc --channel="472.0.246392609\420752452" -greomni "C:\Program Files\Mozilla Firefox\omni.ja" -appomni "C:\Program Files\Mozilla Firefox\browser\omni.ja" -appdir "C:\Program Files\Mozilla Firefox\browser"  472 "\\.\pipe\gecko-crash-server-pipe.472" tab

This is now the 64 bit version of course.

One of your links pointed to Flash as being a possible culprit. Playing videos has seemed somewhat related as they have been running when it hangs. And I've been getting Upgrade Flash messages. Clicking Upgrade or Allow hasn't seemed to have any effect. So that seemed like a good candidate.

Uninstalled Flash. Restarted FF. Video started playing without it. So that may not be as relevant as I'd hoped.

The error can also point to malware - have a look at all the suspicous programs listed in that article’s Step 1.

No sign of any of those listed.

bwhite said

I scanned with Windows Defender last night. No issues. Scanning with the MS Safety Scanner now. Two others scheduled to go tonight.

Of the four, one scanner found some cookies it didn't like. No malware or viruses.

No bad behavior since upgrading to the 64-bit version.

Not directly related but I have a Windows10 machine apparently doing something odd. It seems to have a Firefox install not correctly updating. usually the tips in these articles resolve such issues

• How to fix the Update Failed error message when updating Firefox
• Updates reported when running newest version#w_delete-update-configuration-files

In this case it did not seem to but not yet something I have fully investigated.

I gather from your last post that everything is ok at the moment whilst using Fx 64bit.

John99 said

I gather from your last post that everything is ok at the moment whilst using Fx 64bit.

Just to wrap this up, no issues since upgrading to x64. I ran 4 of the scanners suggested. Most found nothing. One found some cookies it didn't like. Every single day.

I did have once that it said I needed to upgrade to v47. Panic inducing until I realized I had clicked on an old shortcut.

Thanks to everyone for the help trying to track this down. Brad.