Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

How do I open/use Firefox on new W10?

more options

Trying to use MF as usual, nothing works. Downloaded/Installed W10 and everything is Bassackward.

Error msg: WerFault.exe – Application Error The instruction at 0x000000000FFFFFFFF73BF1125 referenced memory at 0x000000000FFFFFFFF.

Cannot even open MF "Troubleshooting File"

Trying to use MF as usual, nothing works. Downloaded/Installed W10 and everything is Bassackward. Error msg: WerFault.exe – Application Error The instruction at 0x000000000FFFFFFFF73BF1125 referenced memory at 0x000000000FFFFFFFF. Cannot even open MF "Troubleshooting File"

All Replies (2)

more options

Sorry to hear about the crashes.

Are you getting the Mozilla Crash Reporter dialog to submit crash reports?

In that case, your Firefox may have logged some data that would help track down the cause of the problem. Please check the last section of the support article "Firefox Crashes" for steps to look up the crash report IDs, and then post some of the recent ones here so volunteers can read them.

Also and/or meanwhile, could you test in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

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 less crashy?

more options

Firefox 40, scheduled to be released this coming week, will have numerous compatibility fixes for Windows 10. Possibly that will address this issue??

Since you seems to be an "early adopter" type person, do you want to try Firefox 40 in its final days of testing?

Note: Some extensions may not be compatible with Firefox 40, especially security suite toolbars that tend to upgrade simultaneously with or shortly after Firefox releases.

The following process will not remove your settings; do NOT uninstall Firefox, that's not needed.

(A) Download a full installer for Firefox 40 "beta" from https://www.mozilla.org/firefox/beta/all/ to a convenient location. (Scroll down to your preferred language.)

Note: to retain use of your installed plugins, I suggest the 32-bit version.

(B) Exit out of Firefox (if applicable).

(C) Rename the program folder, either:

(64-bit Windows folder names)

C:\Program Files (x86)\Mozilla Firefox

to

C:\Program Files (x86)\OldFirefox

(32-bit Windows folder names)

C:\Program Files\Mozilla Firefox

to

C:\Program Files\OldFirefox

(D) Run the installer you downloaded in #1. It should automatically connect to your existing settings.

Any improvement after this install?

Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

  • \OldFirefox\Plugins
  • \OldFirefox\browser\plugins

When the release version of Firefox 40 becomes available (estimated August 11th), I suggest installing that one because beta will auto-update to Firefox 41 shortly thereafter and unless you like testing software, that might be a little more adventure than you're looking for.