Extension icons gone from manage add-ons
My add-ons are functioning. They're still installed. BUT in Add-ons Manager none of them show up! Says, "You don't have any add-ons of this type installed." Head-scratcher!
Alla svar (1)
It is possible that there is a problem with the file(s) that store the extensions registry.
Type about:support in the address bar and press enter.
Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.
Delete all extensions*.* files and compatibility.ini in the Firefox profile folder to reset the extensions registry.
New files will be created when required.
After, restart Firefox.
See "Corrupt extension files":
- http://kb.mozillazine.org/Unable_to_install_themes_or_extensions
- https://support.mozilla.org/kb/Unable+to+install+add-ons
You will have to approve the updating one last time.