Open the Customize window.

• "3-bar" Firefox menu button > Customize

Try to click the Restore Defaults button to restore the default toolbar setup to see if that makes customize work.

• https://support.mozilla.org/kb/customize-firefox-controls-buttons-and-toolbars

1) You can try to reset the browser.uiCustomization.state pref on the about:config page.

2) You can check for problems caused by a corrupted localstore.rdf file.

• http://kb.mozillazine.org/Corrupt_localstore.rdf

What happens if you enter about:customizing in the address bar? You also can try to access the page by entering about:about and clicking on the link there.

Thanks for your quick responses. I'll make this short. I tried all the solutions offered and it's still the same outcome. I'm scratching my head on this one.

Do a clean reinstall and delete the Firefox program folder before (re)installing a fresh copy of the current Firefox release.

• Download the full Firefox installer and save the file to the desktop
  https://www.mozilla.org/en-US/firefox/all/

If possible uninstall your current Firefox version to cleanup the Windows registry and settings in security software.

• Do NOT remove "personal data" when you uninstall your current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including data in profiles created by other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
• (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

• It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
• http://kb.mozillazine.org/Uninstalling_Firefox

Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure NOT to remove personal data when you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data.

If you keep having problems then also create a new profile.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

I'm a pretty stubborn guy when it comes to computer issues and I generally have always sought out solutions to problems that avoid having to uninstall or reinstall software. Given my stubborn nature, I slept on this issue and this morning I came upon a solution, minus some things that I will have to look into further.

The solution: I disabled all of my extensions and this made it so the "Customization" box would show up as it's supposed to. I was able to mostly arrange things the way they were before with some minor exceptions. Having to disable the extensions I use doesn't make the extensions available to drag and drop when using Customize. This puts a damper on what I can and can't put on the Toolbar. Here are the other issues I am seeing:

1 - Adblock Plus will not stay in the Toolbar after reopening Firefox. I have to reselect the option to have it available in the Toolbar. In the list of Extensions, where I am supposed to be able to put a check mark in the box that says "Show in Add on Bar" it won't let me mark the box. 2 - Text to Voice Extension doesn't show up anywhere. I really like this extension but it appears I cannot use it until I can find a way to get it back in the Toolbar. It doesn't even show up in the menu anywhere. 3 - The extension "Default Full Zoom Level" doesn't show the percentage levels like it used to. It shows 100% no matter what level I zoom in or out of (even though the levels are changing).

If all else fails I am going to try and uninstall the problematic extensions, then reinstall, unless someone here knows the solution to these issues? Other than that, the above (disabling extensions) solved the issue of the Customize box not showing up. I'll mark this one as solved but I'm still curious about the extensions not showing issue, albeit I'll be working on it.

Thanks for the help.

It sounds like one of your extensions is blocking your access to your customization page. Disable half of your extensions, restart Firefox, and then try entering the page again. If it works, then the culprit is one of the extensions you disabled, if it doesn't work, then the culprit is likely one of the extensions you left enabled.

Once you find the culprit, you can remove it or contact the developer and wait for an updated version. Can you also post what the problematic extension and mark that as the solution so that others with the same problem can more quickly find what to disable?

Well, I've gone through all my extensions, one by one but Customize only works if they are all disabled. Guess I'll be contacting each one of the developers. I've used Firefox since like version 10 or so and this is the most troublesome yet. Ah well... as with anything, it will be overcome. I'm still a fan.