On 2017-05-27 12:42 +03, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Göktuğ Kayaalp <self@gkayaalp.com>
>> Date: Sat, 27 May 2017 12:22:22 +0300
>> 
>> [...]
>> Error (initialization): Creation of the default fontsets failed:
>> (error Invalid script or charset name: old-italic)
>>
>> [...]
> Please show your fontset-related customizations.

I don't have any such customisations in Emacs.  Just setting the font
for some faces here and there:

,----
| (add-hook 'org-mode-hook
|           (lambda ()
|             (dotimes (n 7)
|               (set-face-attribute
|                (intern (concat "org-level-" (number-to-string (1+ n))))
|                nil :family (gk-font :sans) :overline nil))))
| 
| (set-face-attribute 'default nil
|                       :height gk-font-default-height
|                       :family (gk-font :mono)
|                       :weight 'light)
| 
| (set-face-attribute 'variable-pitch nil
|                       :height (+ 20 gk-font-default-height)
|                       :family (gk-font :serif))
| 
| (loop for attr in '(mode-line mode-line-inactive) do
|         (set-face-attribute attr nil
|                             :height (- gk-font-default-height 10)
|                             :family (gk-font :sans)
|                             :weight 'normal))
| 
|   (set-face-attribute 'header-line nil
|                       :family (gk-font :mono)
|                       :height gk-font-default-height)
| 
|   (set-face-attribute 'forecast-moon-phase nil
|                       :font (gk-font :forecast-moon-phase))
`----


I also have this config file:

~/.config/fontconfig/fonts.conf: