Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

Thanks for the fast reply Fred. Sadly that's not it as actually my firewall was off anyway. I tried enabling it and adding Firefox in but still no change.

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

Hey Fred, Sorry was doing DIY over the weekend so tried to forget about this!

Sadly even in safe mode, it just doesn't boot. You get the very initial bounce of the icon in the dock and then a flash of whatever screen you're on at the time and that's it. Its never got any further than that. I tried deleting and reinstalling while in safe mode but nothing seems to make a difference.

Any other clues as to where to head for?

Let’s do a full clean re-install;

Note: Firefox comes in three or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only> Firefox itself: (Programs Folder) And two folders in the profile of each user on the computer for each Firefox profile for that user.

If you remove the Firefox folder, the user profiles would not be affected.

Download Firefox For All languages And Systems {web link}

Save the file. Then Close Firefox.

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

Windows: C:\Program Files C:\Program Files (x86) Note: Check Both Folders

Mac: Open the "Applications" folder. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it. See Install Firefox on Linux; https://support.mozilla.org/en-US/kb/install-firefox-linux

If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory. http://www.mozilla.org/firefox#desktop ++++++++++++++++++++++++++++ Look for, and remove any Mozilla or Firefox program folders. Do not remove the Mozilla Thunderbird folder if there is one.

Do Not remove any profile folders.

After rebooting the computer, run a registry scanner if you have one. Then run the installer. +++++++++++++++++++++++++++ If there is a problem, start your Computer in safe mode and try again.

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode This shows how to Start all Computers in Safe Mode; Free Online Encyclopedia

Hi Fred,

Nope sadly no change. I have done this several times already. But tried it again just to be sure and actually it was an upgrade as I had downgraded to v74 just as a test, but now on v75 but no joy.

I called for more help.

Thanks for your help so far Fred.

Does anyone else have any clues about how I can get Firefox up and running again. This is stopping me from accessing a specific website that apparently needs Firefox to get to it.

Incidentally I just tried opening Firefox in a guest account and it opened fine so it is definitely something in my account that is stopping it. Maybe if someone has a definitive list of any possible cache files or something like that that may be stopping it from booting, I'd really appreciate that.

Thanks in advance for your help.

I just tried opening Firefox in a guest account and it opened fine

Keep using that profile. Any problems?

Once you are sure,

Use these links to create a new profile. Use this new profile as is. Is the problem still there?

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Type about:profiles<enter> in the address bar.

Hey Fred,

Again thanks for your time. Sadly still no joy.

In the guest user account on my Macbook Pro, then Firefox boots up fine and I can surf etc no problem. I have tried copying the profile details from that account to my main user account and no joy. No matter how I try and copy the info over, nothing ever works.

I've tried renaming the Firefox file in Application support and watched as the moment I try and boot up Firefox, it rebuilds that folder and contents but thats' where it stops. Literally once bounce of the app in the dock and that's your lot.

I've read through all those docs and tried all things suggested but just no go. Somewhere there is a gremlin and it seems no amount of trying will get me past the starting block!

OK I have spent a whole day backing up my MBP, making a separate instance of Mojave so that I can still keep my 32bit apps that haven't been updated yet, then upgraded to Catlina, just in case there was something weird going on there but still no joy!

Have tried deleting and re installing again, tried creating new profiles, still nothing. And yet still if I go to a guest user account, it boots perfectly, so it has to be something on my user account that is holding it back. If anyone has any bright ideas what this could be I'd really appreciate it as this is getting boring now!

Thank you!

Cancel that I've solved it! For anyone else that this happens to....

While going to terminal and going through the create new profile scenario, I just noticed the following line of text that came up if you clicked on Start Firefox rather than exit:

The patch directory path is not valid for this application (/Users/mr.b./Library/Caches/Mozilla/updates/Applications/Firefox/updates/0)

I looked at this folder and the dates seemed weird on the folder and files and folders within, considering I have installed and re-installed several times over the last few days and the dates were things like 7th April, 9th April. I figured as it wasn't working at all at the moment, what's the worst that can happen, so I deleted that folder, and restarted Firefox and it came up immediately.

So if this ever happens to you, head for that Updates folder in the caches folder for Firefox, bin it and see fi it solves your problem.

Many thanks to Fred for trying many times to get me going, I really appreciate your time.

That was very good work. Well Done.