CTR would normally appear under the Extensions tab. What you see under Appearance would be lightweight themes (background images for the toolbar area) or complete themes.

Can you attach a screenshot?

• https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem
• use a compressed image type like PNG or JPG to save the screenshot

See also:

• https://support.mozilla.org/en-US/kb/disable-or-remove-add-ons

Hi   !
Would you take a look at the article :
Cannot remove an add-on (extension or theme)
Especially the section :   'Uninstalling manually'.

What would you like a screenshot of?

I've uploaded the mention of the add-on. Surely this is the only one named "Classic Theme Restorer"?

The image is from <https://addons.mozilla.org/en-US/firefox/extensions/appearance/>

This "Classic Theme Restorer" link gets me to the problem page, which has no disable or remove buttons.

@Happy12

about:plugins lists only 2 plugins:

OpenH264 Video Codec provided by Cisco Systems, Inc. and Widevine Content Decryption Module provided by Google Inc.

FFzuki7 said

@Happy12 about:plugins lists only 2 plugins: OpenH264 Video Codec provided by Cisco Systems, Inc. and Widevine Content Decryption Module provided by Google Inc.

How about :   Add-ons => Extensions   ?

@Happy12

Not sure what you mean by "Add-ons => Extensions".

But "about:extensions" gets me "The address isn’t valid"

With Add-ons => Extensions I meant : 3-bar menu => Add-ons => Extensions, which makes no sense, as Classic Theme Restorer is installed in Appearance (sorry   !)
As I never used CTR , I have no way to check if and how the add-on can be disabled. Classic Theme Restorer will however stop working in November, see :
About this Add-on This add-on will stop working when Firefox 57 arrives in November 2017 and Mozilla drops support for XUL / XPCOM / legacy add-ons. It should still work on Firefox 52 ESR until ESR moves to Firefox 59 ESR in 2018 (~Q2).
Also see :
https://www.ghacks.net/2017/03/08/the-death-of-classic-theme-restorer-for-firefox/

The address of the page that shows your installed extensions is about:addons

You posted a screenshot of the Add-ons website and that doesn't show installed extensions, but shows a list of extensions that you can consider to install. If you only see CTR on the Add-ons website and do not have this extension installed then there shouldn't be any problem.

Yes, about:addons and selecting "extensions" in the left hand column does show a list of extensions I've installed.

See the attached screen shot of the list before I disabled CTR.

FFzuki7 said

Yes, about:addons and selecting "extensions" in the left hand column does show a list of extensions I've installed. See the attached screen shot of the list before I disabled CTR.

In your first post you say :

there isn't any button or whatever to either disable or turn off "Classic Theme Restorer"   ..........   (?)

You can click the Remove button next to CTR to remove the CTR extension if you haven't done this yet. :wink:

Thanks to you guys I'm gradually making my way around Mozilla World.