Customize variable: custom-theme-load-path[no match]

Question

1. I followed instruction here to erase customization. however, it returns [no-match]. am i doing anything wrong here?

2. The reason that I was trying to erase the custom-theme-load-path is that I failed to load color theme from .init file, in the following way. any hint on why it failed to load the solarized theme? Any help is appreciated!

having the following piece in a file general-settings.el

(add-to-list 'custom-theme-load-path (make-plugin-path "color-theme-solarized"))
(load-theme 'solarized 1)

and then (require 'general-settings) in my .init file

make-plugin-path is defined as below:

(defun make-plugin-path (plugin)
  (expand-file-name
   (concat plugin-path plugin)))

plugin-path is a defined variable

Answer 1

Exactly the question you have linked lead to the decision to demote custom-theme-load-path from defcustom to defvar in Emacs 25.0.90.

For that reason it is no longer customizable by customize.

The corresponding commit was 995b69918b with title "custom.el (custom-theme-load-path): Demote to defvar".

I cite here the comment of that commit:

custom-theme-load-path was a defcustom, but it shouldn't be for the same reason that load-path shouldn't. Setting it via the customize interface is a trap for the user.

Installed themes commonly add themselves to this variable, which means its value is not fit for being saved (it will permanently remember dirs that don't exist anymore).

This is aggravated by the fact that Emacs always applies the 'user' theme on top of any theme that's loaded, since this will apply the old variable value and remove any new directories that had been recently added by themes themselves.

Not to mention, we already have custom-theme-directory, which is safe to customize.