Fatal error: Uncaught Error: Interface "Composer\Plugin\PluginInterface" not found in /var/www/unitedcomputerservice.com/htdocs/wp-content/plugins/gantry5/vendor/composer/installers/src/Composer/Installers/Plugin.php:9 Stack trace: #0 {main} thrown in /var/www/unitedcomputerservice.com/htdocs/wp-content/plugins/gantry5/vendor/composer/installers/src/Composer/Installers/Plugin.php on line 9