Template is missing appears as an error in your WordPress admin section when there’s an issue with your theme stylesheet header (the commented section in your style.css).
In the child theme example below you’ll notice the line ‘Template: twentyfifteen‘.
/* Theme Name: Twenty Fifteen Child Theme URI: http://wordpress.com/twenty-fifteen-child/ Description: Twenty Fifteen Child Theme Author: John Doe Author URI: http://example.com Template: twentyfifteen Version: 1.0.0 License: GNU General Public License v2 or later License URI: http://www.gnu.org/licenses/gpl-2.0.html Tags: light, dark, two-columns, right-sidebar, responsive-layout, accessibility-ready Text Domain: twenty-fifteen-child */
The Template line needs to show the directory path of your parent theme. The template for the Twenty Fifteen example (/wp-content/themes/twentyfifteen) would be twentyfifteen.
I hope that helps!
Many thanks..really helped me and saved my time!