Custom WordPress install - activate custom theme

Question

I'm coding my own custom install.php (wp-content) and I want to be ablt to activate my custom theme when an install is running. Right now I've tried switch_theme('theme-slug') which works, however when I first log in to my admin panel, all the admin pages under Settings etc. is gone, so something is not right. If I remove switch_theme function from my install.php, then it tries to activate "twentyseventeen" however it can't find that theme, and that's because I've removed it from the themes folder, because I want to activate my own theme called "mastertheme".

Can somebody help me on how to activate my own theme when WordPress installs?

Answer 1

Twenty Seventeen is the default theme if no default theme has been defined. line 359 from wp-includes/default-constants.php

if ( !defined('WP_DEFAULT_THEME') )
        define( 'WP_DEFAULT_THEME', 'twentyseventeen' );

You do not need to edit that file, however, to change this.

Simply define your theme in the file wp-config.php just before this line:

require_once(ABSPATH . 'wp-settings.php');

Like so:

define( 'WP_DEFAULT_THEME', 'my-new-default-theme' );
require_once(ABSPATH . 'wp-settings.php');