WordPress theme editor is missing

Open up your wp-config.php file, and search for

define('DISALLOW_FILE_EDIT', true);

Change true to false:

define('DISALLOW_FILE_EDIT', false);

It is probably because of iThemes Security and its settings. So yeah, just go to wp-config and change DISALLOW_FILE_EDIT to false.

define( 'DISALLOW_FILE_EDIT', false );

Or just switch it off here: Dashboard -> Security -> WordPress Tweaks -> Configure Settings

Uncheck: Disable File Editor

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