Here are a couple of places to check your plugins and extensions.

(1) Plugins

Type or paste about:plugins in the address bar and press Enter. This should open a long page showing which content types are handled by which plugins.

Note: when reading the "State" line, "Enabled" can mean either "Always Activate" or "Ask to Activate", and "Disabled" means "Never Activate".

(2) Extensions

You can find a list and their current Enabled/Disabled status on the Troubleshooting Information page. Either:

• "3-bar" menu button > "?" button > Troubleshooting Information
• Help menu > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

Extensions are listed in the second table on the page.

To get back to the problem of your broken Add-ons page, I don't have an immediate idea of what's going wrong there. In case one of your extensions is involved, could you test the page 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.

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

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Any difference?

"about:plugins" gives me a blank white screen. No information whatsoever.

"about:support" gives me.... well see for yourself. http://imgur.com/qdbdsnA That's no help either.

Restarting with add-ons disabled makes Firefox crash.

Try to delete the pluginreg.dat file in the Firefox Profile Folder and maybe addons.sqlite as well to reset the plugin registry databases.

See Re-initializing the plugins database:

• https://support.mozilla.org/kb/troubleshoot-issues-with-plugins-fix-problems

You can check for issues caused by plugins and set all plugins to "Ask to Activate" on the "Firefox/Tools > Add-ons > Plugins" page (plugins are not affected by Firefox Safe Mode)

• https://support.mozilla.org/kb/Troubleshooting+plugins

It is possible that there is a problem with the file(s) that store the extensions registry.

Delete the extensions.* files (e.g. extensions.json, extensions.sqlite, extensions.ini) and compatibility.ini in the Firefox profile folder to reset the extensions registry.

• https://support.mozilla.org/kb/Profiles

New files will be created when required.

See "Corrupt extension files":

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions
• https://support.mozilla.org/kb/Unable+to+install+add-ons

If you see disabled or not compatible extensions in "Firefox/Tools > Add-ons > Extensions" then click the Tools button at the left end of the Search bar to check if there is a compatibility update available.

If this hasn't helped then also delete possible addons.json and addons.sqlite files.

<<Delete the extensions.* files (e.g. extensions.json, extensions.sqlite, extensions.ini) and compatibility.ini in the Firefox profile folder to reset the extensions registry.>>

Tried this but files can't be deleted because Firefox in use? So tell me how to do it please.

Hi dolejast, please exit Firefox before deleting any of its settings files.

If all else fails, you could try:

Create a new Firefox profile

A new profile will have your system-installed plugins (e.g., Flash) and extensions (e.g., security suite toolbars), but no themes, other extensions, or other customizations. It also should come with completely fresh settings databases and a fresh cache folder.

Exit Firefox and start up in the Profile Manager using Start > search box (or Run):

firefox.exe -P

Don't delete anything here.

Any time you want to switch profiles, exit Firefox and return to this dialog.

Click the Create Profile button, assign a name like 1209, and ignore the option to change the folder location. Then start Firefox in the new profile you created.

Do the Add-ons page, about:plugins, and about:support load normally in the new profile?

If so, it sounds like a settings problem. If not, it could be corruption of Firefox's program files. See the "Clean Reinstall" section below.

When returning to the Profile Manager, you might be tempted to use the Delete Profile button. But... it's a bit too easy to accidentally delete your "real" profile, so I recommend resisting the temptation. If you do want to clean up later, I suggest making a backup of all your profiles first in case something were to go wrong.

To keep the new profile and migrate data, check out this article: Recovering important data from an old profile.

Clean Reinstall

(1) Download a fresh installer for Firefox 34 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.)

(2) Exit out of Firefox.

(3) Rename the program folder

(32-bit Windows folder names)

C:\Program Files\Mozilla Firefox

to

C:\Program Files\OldFirefox

(64-bit Windows folder names)

C:\Program Files (x86)\Mozilla Firefox

to

C:\Program Files (x86)\OldFirefox

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

When starting Firefox, you may need to use the profile manager to switch back to your regular profile.

Do the Add-ons page, about:plugins, and about:support load normally with the new program files?

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

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

<<Hi dolejast, please exit Firefox before deleting any of its settings files.>>

How can I exit Firefox and still access the settings files? If I knew how to do this then it would be a lot easier.

Hi dolejast, good question. Here's how I suggest doing it:

Use the button in Firefox to open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Show Folder" button. This should launch a separate window (Windows Explorer window) listing the contents of the profile folder.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then the file locks should be released and you can rename, move or delete files. (Carefully, of course, since some files contain valuable data like bookmarks, passwords, and add-on data.)

Here's the problem. Even though I close Firefox window it is still running in the processes so I still can't make any canges and when I end the process in the settings window everything closes. Got any advice for that one?

Hi dolejast, I'm not sure what you mean by "everything closes". Windows besides Firefox windows close when you End Process on firefox.exe? That seems wrong.

I suppose one workaround would be to create a shortcut to your Firefox profile folder on your desktop. Then you can easily open it the next time you shut down and restart Windows when for sure Firefox will not be running (assuming you haven't set up Windows to start Firefox automatically). To create the shortcut, make sure the desktop is visible then drag the yellow folder from the address bar of Windows Explorer and drop it on the desktop.

Sorry for the confusion. I open the folder in the profile containing the offending items to be deleted or renamed. Then I close Firefox. I am still unable to make any deletions or changes. I get a pop up that says Firefox is still running. I open the task manager and even though the Firefox program is on listed, when I go to the processes window, there it is. I end the process and of course my saved window disappears. Back to square one. Virus? Toolbar snafu? (haven't added one in recent memory) Should I try running antivirus/antimalware programs? Do you think that may of any benefit?

It may help to run some scanning and cleaning tools. We list various free ones in our support article: Troubleshoot Firefox issues caused by malware. Those take quite a while to run. If they finish quickly and ask for payment, you may have a more serious infection. The forums listed in the article are recommended in that case.

You also could try the new profile test and clean reinstall I described in the earlier post: https://support.mozilla.org/questions/1018609#answer-662450

I have a couple of programs which I can run. I will get back to you later, maybe not today. I have much to do. Thanks.