Firefox Add-on will not uninstall completely

Question

Symptom

An Add-on is still listed in Add-On Manager-Extensions, after it has been uninstalled and Firefox restarted. No matter how many times Firefox is restarted, the listing is still visible, along with this message:

This add-on will be uninstalled after Firefox is restarted.

How do I remove (uninstall) the Add-on from the Firefox Add-On Extension List?

Answer 1

Cause

The Add-on extension still exists in the FIREFOX EXTENSIONS FOLDER:

C:\Documents and Settings[user_name]\Application Data\Mozilla\Firefox\Profiles[random_number].default\extensions

Solution

In Firefox,

1. Uninstall the extension using Add-On Manager.
2. RESTART FIREFOX.
3. Go to HELP / TROUBLESHOOTING INFORMATION...
4. Find the Add-on name and note the extension number.
5. Drill down to the Firefox extensions folder (see quote immediately above).
6. Delete the extension number that corresponds to the Add-on name.
7. CLOSE FIREFOX.
8. Next find file called EXTENSIONS.RDF (it is XML format). BACKUP THIS FILE
9. Open EXTENSIONS.RDF with a text editor, and look for the extension number.
10. There are two occurrences.
11. One occurrence is single line (a declaration line). Delete the entire line.
12. Another occurrence has an opening and closing tag, with several lines in between.
13. Delete everything within the opening and closing tags, including the tags themselves.

Open Firefox to make sure it works properly.

Open Add-On Manager. There should be no trace of the Add-on name in the list.

This procedure appears to work with other ill-behaved uninstallers that leave entries behind.