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Warning: require_once(ABSPATHwp-admin/includes/class-wp-upgrader.php): failed to open stream: No such file or directory in /var/www/html/wp-content/plugins/one-click-demo-import/inc/PluginInstallerSkinSilent.php on line 11

Fatal error: require_once(): Failed opening required 'ABSPATHwp-admin/includes/class-wp-upgrader.php' (include_path='.:/usr/share/php') in /var/www/html/wp-content/plugins/one-click-demo-import/inc/PluginInstallerSkinSilent.php on line 11