Fatal error: Uncaught Error: Interface 'Composer\Plugin\PluginInterface' not found in /srv/www/c5www/html/updates/concrete5-8.5.1/concrete/vendor/wikimedia/composer-merge-plugin/src/MergePlugin.php:82 Stack trace: #0 {main} thrown in /srv/www/c5www/html/updates/concrete5-8.5.1/concrete/vendor/wikimedia/composer-merge-plugin/src/MergePlugin.php on line 82