Hi Matt, this has been going on for 9-10 months? Usually if Firefox shuts down without any error or explanation, it was "killed" by Windows. Could you check the Windows "Applications" Event Log to see whether it mentions the event?

In the Windows 10 search box on the taskbar, type event. In the results, you should see Event Viewer Desktop App. Click that. It takes a little while to start up.

In the left column, expand Windows logs and click Application.

You'll see the most recent events first and you can use the time to try to drill down on Firefox events. If you find the crash there, you can right-click that row in the upper table, click Copy, then click Copy Details as Text. When you paste that, there may be some extraneous stuff at the end that isn't needed, but it's hard to say for sure.

Hi, thanks for responding.

Yes, I've been looking for a solution for some time. My work around is to open another browser whenever I have to upload anything.

Here is the info you requested (I also found a Report.wer file but that might be too much detail at first):

Log Name: Application Source: Application Error Date: 04/08/2019 9:49:09 AM Event ID: 1000 Task Category: (100) Level: Error Keywords: Classic User: N/A Computer: xxxxx Description: Faulting application name: firefox.exe, version: 66.0.2.7024, time stamp: 0x5c9a7ba9 Faulting module name: ntdll.dll, version: 10.0.17763.348, time stamp: 0xca65c822 Exception code: 0xc0000409 Fault offset: 0x000000000008fb3f Faulting process id: 0x569c Faulting application start time: 0x01d4eaed78b4142a Faulting application path: C:\Program Files\Mozilla Firefox\firefox.exe Faulting module path: C:\WINDOWS\SYSTEM32\ntdll.dll Report Id: 25456391-fc39-409d-bb17-8d06a4c31bb1 Faulting package full name: Faulting package-relative application ID: Event Xml: <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">

 <System>
   <Provider Name="Application Error" />
   <EventID Qualifiers="0">1000</EventID>
   <Level>2</Level>
   <Task>100</Task>
   <Keywords>0x80000000000000</Keywords>
   <TimeCreated SystemTime="2019-04-08T13:49:09.713054000Z" />
   <EventRecordID>20478</EventRecordID>
   <Channel>Application</Channel>
   <Computer>xxxxx</Computer>
   <Security />
 </System>
 <EventData>
   <Data>firefox.exe</Data>
   <Data>66.0.2.7024</Data>
   <Data>5c9a7ba9</Data>
   <Data>ntdll.dll</Data>
   <Data>10.0.17763.348</Data>
   <Data>ca65c822</Data>
   <Data>c0000409</Data>
   <Data>000000000008fb3f</Data>
   <Data>569c</Data>
   <Data>01d4eaed78b4142a</Data>
   <Data>C:\Program Files\Mozilla Firefox\firefox.exe</Data>
   <Data>C:\WINDOWS\SYSTEM32\ntdll.dll</Data>
   <Data>25456391-fc39-409d-bb17-8d06a4c31bb1</Data>
   <Data>
   </Data>
   <Data>
   </Data>
 </EventData>

</Event>

What you posted above is information about your computer that is attached to the crash report and that doesn't include the GUID of the crash report.

If you have submitted crash reports then please post the IDs of one or more recent crash reports that start with "bp-".

• bp-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

You can find the report ID of recent crash reports on the "Help -> Troubleshooting Information" (about:support) page.

• click the "All Crash Reports" button on this page to open the about:crashes page and see all crash reports.

Alternatively you can open about:crashes via the location/address bar.

See also:

• https://support.mozilla.org/en-US/kb/Mozilla+Crash+Reporter

cor-el: when I type about:crashes, there is no crash listed

If there aren't any crashes listed then this means that either the crash reporter is disabled or didn't get triggered.

Are there any pending reports in the "Crash Reports" folder in the profile folder or in the parent folder? You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:preferences page. Go up one or two levels until you see the "Crash Reports" folder.

• C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\
• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Okay. I found the "Crash Reports" folder. There's a couple of empty directories: "events" and "pending", then a bunch of files that start with "InstallTime" with a date after. These files only contain one number. The most recent is "InstallTime20190326175229". That's all that is in the folder.

Thank you for the Windows crash data. I don't see "Problem Event Name" in the paste, which could be a change in Windows 7 vs. Windows 7.

Matt said

Faulting application name: firefox.exe, version: 66.0.2.7024, time stamp: 0x5c9a7ba9
Faulting module name: ntdll.dll, version: 10.0.17763.348, time stamp: 0xca65c822
Exception code: 0xc0000409

That "Exception code" is associated with a stack overflow, but unfortunately that doesn't point me toward a solution.

Have you ever tested in Firefox's Safe Mode? In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, any userChrome.css/userContent.css files, 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. (On Mac, hold down the option/alt key instead of the Shift key.)

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

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

No, it still crashes in safe mode. I posted about this error last year, but no one could help. You can see the steps I took last year to work on it if you search for other posts by me.

You can try to clear the Windows MRU lists.

I don't know if this hasn't changed in Windows 10. Navigate to: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\ComDlg32 Delete the subkeys (LastVisitedPidlMRU and OpenSavePidlMRU) Be cautious with editing the registry as there is no Undo possible: all changes are applied immediately. You can export registry keys before making changes.

There are a lot of values under the OpenSavePidIMRU. I'm reluctant to delete it because I'm concerned it will make changes for a lot of programs. If this is likely going to help, can you at least explain what I'm changing by deleting this?

I've been through a lot of these suggestions already last year (see https://support.mozilla.org/en-US/questions/1222459). I got to the point where it seemed like I'd found a solution, but then it was right back to doing it again.

This seems like a fairly narrow problem because it always happens when I try to upload a file. Can anyone provide some more definite steps of how to troubleshoot this rather than one step at a time?