Fatal error: Uncaught TypeError: ftp_nlist(): Argument #1 ($ftp) must be of type resource, null given in /home/www/wp-admin/includes/class-wp-filesystem-ftpext.php:420
Stack trace:
#0 /home/www/wp-admin/includes/class-wp-filesystem-ftpext.php(420): ftp_nlist(NULL, '/home/www/')
#1 /home/www/wp-admin/includes/class-wp-filesystem-base.php(228): WP_Filesystem_FTPext->exists('/home/www/')
#2 /home/www/wp-admin/includes/class-wp-filesystem-base.php(57): WP_Filesystem_Base->find_folder('/home/www/')
#3 /home/www/wp-content/plugins/mainwp-child/class/class-mainwp-security.php(339): WP_Filesystem_Base->abspath()
#4 /home/www/wp-content/plugins/mainwp-child/class/class-mainwp-security.php(50): MainWP\Child\MainWP_Security::remove_readme()
#5 /home/www/wp-content/plugins/mainwp-child/class/class-mainwp-child.php(284): MainWP\Child\MainWP_Security::fix_all()
#6 /home/www/wp-includes/class-wp-hook.php(307): MainWP\Child\MainWP_Child->parse_init('')
#7 /home/www/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters(NULL, Array)
#8 /home/www/wp-includes/plugin.php(476): WP_Hook->do_action(Array)
#9 /home/www/wp-settings.php(598): do_action('init')
#10 /home/www/wp-config.php(77): require_once('/home/www/wp-se...')
#11 /home/www/wp-load.php(50): require_once('/home/www/wp-co...')
#12 /home/www/wp-blog-header.php(13): require_once('/home/www/wp-lo...')
#13 /home/www/index.php(17): require('/home/www/wp-bl...')
#14 {main}
thrown in /home/www/wp-admin/includes/class-wp-filesystem-ftpext.php on line 420