Featured image box

Hello,

in the editor the Featured image is not shown at the top right of posts and portfolio items so it is unmanageable. Furthermore, there are broken theme messages even though I reinstalled the theme and in the other installation the same version does not create problems.
Error: Template is missing. Standalone themes need to have a templates/index.html or index.php template file. Child themes need to have a Template header in the style.css stylesheet. Broken Themes
The following themes are installed but incomplete.
Name Description
enfold-child Template is missing. Standalone themes need to have a templates/index.html or index.php template file. Child themes need to have a Template header in the style.css stylesheet.

As usual, thanks in advance for your help
Andrea