I have the follow error message on the WordPress dashboard

Warning: Invalid argument supplied for foreach() in /home/customer/www/reallysimpleguitar.com/public_html/wp-content/plugins/wordpress-starter/core/Pages/Themes.php on line 191

I’m not able to add any plugins to the site either (the option is not available on the left menu bar) I think it may be related?

Any help would be apprecaited.

Thank you!