Hmm, usually a BEX error (buffer overflow) is associated with malware. However, in another thread, a user mentioned that if Spybot Search & Destroy is running, Firefox 54 crashes on exit. So possibly it could be related to some security software.

If you use SSD, can you turn off any features that might modify Firefox in use?

No malware, SpyBot not running in the bakcground, no SSD. Thanks anyway

Do you exit Firefox using the menu or using the "X" button? If you don't normally used the menu, could you try it? Either:

• "3-bar" menu button > power symbol
• (menu bar) File > Exit

If that makes no difference, could you test whether the same problem occurs exiting from Firefox's Safe Mode?

In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement? (More info: Diagnose Firefox issues using Troubleshoot Mode)

Thanks, I know how to Safe Mode. Same error.

Mind you: this problem MAY have the same root cause(s) as my previous one: Firefox 53 the cause of Windows freezing?

It is not clear if all this is really caused by FF itself, or by it not being handled well by Windows (7 x64 SP1).

jscher2000 said

Do you exit Firefox using the menu or using the "X" button? If you don't normally used the menu, could you try it?

Sorry, forgot that one. Tried it: same sad story.

0.51 AM Local: bed time. Will pick up tomorrow. Thanks for any input.

Oh, your other thread already has over 40 replies, so it probably makes sense to add this issue there.

Do a malware check with several malware scanning programs on the Windows computer.

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

jscher2000 [[#answer-978053|said]

Oh, your other thread already has over 40 replies, so it probably makes sense to add this issue there.

I already did a few posts back, but here it is again: https://support.mozilla.org/questions/1158873

cor-el said

Do a malware check with several malware scanning programs on the Windows computer.

1. Because of WannaCry and other nsa-like crap, I recently deep scanned my well protected & up-to-date system with most of the tools you describe, but nothing found. I didn't know Microsoft Safety Scanner, but ran it and nothing found either. 2. The issue does not show any malware/virus-like behaviour. 3. The problem first occurred after updating to FF54.

I reverted back to FF53.0.3 and guess what? No more BEX error!

As I tried to make clear: this has nothing to do with malware/viruses. FF54's new multiple processes ‘Electrolysis ’ (or E10s) is probably the cause.

If you try in Firefox's safe mode AND in Windows 7 safe mode at the same time do you still get the same issue ?

Also is this issue associated with any specific website ?

Please try this:

1. For instance if you open Firefox with only its default homepage open, and then close Firefox without doing any browsing and use the Menu button {3 bar icon) ==> Quit {Standby icon) do you still get the BEX crash ?
2. If that is problem free then what happens if you browse but only on this support forum before closing Firefox ?
3. I don't think we ever tried a clean reinstall of Firefox. That is not something that is guaranteed to help but it certainly should be tried. It involves removing the Firefox program folder (NOT the Firefox Profile folder & files)

Clean Reinstall

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove your Firefox program files and then reinstall Firefox. This process does not remove your Firefox profile data (such as bookmarks and passwords), since that information is stored in a different location.

To do a clean reinstall of Firefox, please follow these steps: Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from mozilla.org (or choose the download for your operating system and language from this page) and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (or open the Firefox menu and click the close button ).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here.

WARNING: Do not use a third party uninstaller as part of this process. Doing so could permanently delete your Firefox profile data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be easily recovered unless they have been backed up to an external device! See Back up and restore information in Firefox profiles.

wwwaste said

I reverted back to FF53.0.3 and guess what? No more BEX error! As I tried to make clear: this has nothing to do with malware/viruses. FF54's new multiple processes ‘Electrolysis ’ (or E10s) is probably the cause.

Yes but the problems with downgrading are

1. You have had problems in Fx53, are these now resolved ?
2. Firefox 53 should now be considered not to be safe or secure. You should not now use it.
   • See (Do Not) Install an older version of Firefox

John99 said

1. You have had problems in Fx53, are these now resolved ? 2. Firefox 53 should now be considered not to be safe or secure.

1. Yes after a cleanup 2. I'm aware of the implications, but I prefer not to get my os ruined by FF54's E10.

I am not sure anyone is able to say the issue is soley down to E10s and if it was it is possible to disable that. (Unfortunately the easy methods of tweaking E10s may be in later versions of Firefox.)

I am not sure but are you saying you have turned off E10s on Fx54 and the BEX issue then goes away? or are you presuming any issue with Fx54 must be E10s related therefore your BEX issue is E10s related.

John99 said

I am not sure anyone is able to say the issue is soley down to E10s and if it was it is possible to disable that. (Unfortunately the easy methods of tweaking E10s may be in later versions of Firefox.) I am not sure but are you saying you have turned off E10s on Fx54 and the BEX issue then goes away? or are you presuming any issue with Fx54 must be E10s related therefore your BEX issue is E10s related.

I'm not sure either if FF54's E10s or the sandbox implementation as such is the cause, but I do know the BEX error only occured after updating from FF53 to FF54. Reverting to FF53 solves the problem.

No, I did not turn off/tweaked FF54's E10s (wouldn't know how to do that anyway).

Firefox 53 is now unsupported and must be considered unsafe. If you must use an older version of Firefox temporarily whilst sorting out problems with the current Release (Fx54) you should use Fx52 ESR because at least that has critical security fixes and so is safe to use.

Further as you are a Windows user the simplest method may be to install the third party build Firefox Portable ESR (Currently Fx52.2.0) as an additional browser.

• https://portableapps.com/apps/internet/firefox-portable-esr

Thanks.

Eagerly awaiting a follow up on solving the FF54 problem...

wwwaste said

No, I did not turn off/tweaked FF54's E10s (wouldn't know how to do that anyway).

If you're willing to give it a try :

You could turn it off as follows :

Type in the address bar about:config (promise to be careful, if asked) Type and search for the preferences : browser.tabs.remote.autostart and set it's value to false browser.tabs.remote.autostart.2 and set it's value to false

Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

Happy112 said

If you're willing to give it a try : You could turn it off as follows : Type in the address bar about:config (promise to be careful, if asked) Type and search for the preferences : browser.tabs.remote.autostart and set it's value to false browser.tabs.remote.autostart.2 and set it's value to false Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

Thanks. Did that already, but didn't solve the BEX error.

Would you consider posting this on the Microsoft support forum   ? (It's pretty similar to this forum)

https://answers.microsoft.com/en-US/windows/forum/windows_10

Or the Dutch section :

https://answers.microsoft.com/nl-nl/site/startsignin