That's frustrating. Some "cleaning" programs that run at Windows startup may modify your browser settings. Can you make sure they are not touching Firefox settings files?

The next time this happens, could you check whether this is a problem of a broken Add-ons page or whether the extensions were actually removed? One reason for the Add-ons page to have a blank extensions list would be some corruption in Firefox's database of extensions. You can force Firefox to regenerate the files by doing the following:

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 new window listing various files and folders in Windows Explorer.

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 rename any of these files that you find:

• compatibility.ini to something like compatibility-old.ini
• extensions.ini to something like extensions-old.ini
• extensions.json to something like extensions-old.json
• extensions.sqlite to something like extensions-old.sqlite (might not exist depending on how long you've been using this settings folder)

When you start Firefox back up again, it should explore your profile folder and other folders to rebuild the list. It probably will ask you to approve some of the extensions. Once things settle down, could you check the Add-ons page again.

Do the extensions reappear -- or are they truly gone?

Also, you may want to start backing up your Firefox profile folder containing your settings. This article has tips on that: Back up and restore information in Firefox profiles.

Also, the forum software detected your Firefox as version 34.0.5. Is that correct?

Version 34 is not secure; Mozilla discloses security flaws after each new release. Is something holding you back from upgrading to Firefox 42? Please let us know so we can suggest solutions or workarounds.

If Help > About Firefox shows Firefox 42.0, you may need to clear the preference that is misreporting your version number. See: How to reset the default user agent on Firefox.

Hi,

I have used auto-update since version 34.0.5, hence I have no more recent version to try... Updated to version 42.0 and deleted the files that you suggested except extensions.sqlite which does not exist..

On restarting Firefox my 5 extensions were offered for installation, now I have them all back... I will see if they get deleted, or whether this is a full solution... I have also taken a copy of my profile as you suggested..

Thanks for the info

Tunnel-Dave

Problem now solved, I think...

A dubious program called Malware Protection Live had installed itself as a running process, showing a green tick on the taskbar... uninstalling this program has stopped my extensions from mysteriously disappearing...

Regards

Tunnel-Dave