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FF39 silently fails to start after upgrade (Win7 64)

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  • 3 have this problem
  • 24 views
  • Last reply by FredMcD

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Upgraded to FF39 this morning and now browser won't start. Watching Task Manager I can see the firefox.exe process flick in and out of existence as if it is dying on startup. No crash reporter, no crash log under %APPDATA%.

Running firefox -P from the command line opens the Profile Manager OK, but when I click "Start Firefox" the browser does not start in the same way as above.

I created a completely new profile in profile manager, clicked "Start Firefox" and the browser does not start either.

I also tried "firefox -no-remote" and that didn't start either.

"firefox -console" opens and closes a console window immediately with no transcript.

I have gone through the suggestions in "No Error Message" here;

https://support.mozilla.org/en-US/kb/firefox-wont-start-find-solutions

Any suggestions gratefully received - is there any way to get a verbose log of what FF is doing when it starts up so I can see where it is failing?

Upgraded to FF39 this morning and now browser won't start. Watching Task Manager I can see the firefox.exe process flick in and out of existence as if it is dying on startup. No crash reporter, no crash log under %APPDATA%. Running firefox -P from the command line opens the Profile Manager OK, but when I click "Start Firefox" the browser does not start in the same way as above. I created a completely new profile in profile manager, clicked "Start Firefox" and the browser does not start either. I also tried "firefox -no-remote" and that didn't start either. "firefox -console" opens and closes a console window immediately with no transcript. I have gone through the suggestions in "No Error Message" here; https://support.mozilla.org/en-US/kb/firefox-wont-start-find-solutions Any suggestions gratefully received - is there any way to get a verbose log of what FF is doing when it starts up so I can see where it is failing?

Chosen solution

It sounds like two possibilities. 1) Firefox was corrupted. 2) Something on your system is blocking Firefox.


Start your Computer in safe mode with networking. Then start Firefox. Try Safe web sites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia


Download Firefox Full Version For All languages And Systems {web link} Save the file. Then;

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86) Mac: Open the "Applications" folder. Linux: Check your user manual.

• 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.


Look for, and rename any Mozilla or Firefox folders by adding .old to them.

Now run the full installer. If all goes well, remove the OLD folders when you are done.

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Chosen Solution

It sounds like two possibilities. 1) Firefox was corrupted. 2) Something on your system is blocking Firefox.


Start your Computer in safe mode with networking. Then start Firefox. Try Safe web sites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia


Download Firefox Full Version For All languages And Systems {web link} Save the file. Then;

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86) Mac: Open the "Applications" folder. Linux: Check your user manual.

• 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.


Look for, and rename any Mozilla or Firefox folders by adding .old to them.

Now run the full installer. If all goes well, remove the OLD folders when you are done.

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Removing the original installation directory was what was required - simply uninstalling the old version was insufficient.

Thanks for the help!

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Glad to help. Safe surfing.