We are using Flatbase 2.0.8 and NiceFramework 2.0.9 and need to update to php 8.1.
But we get the following exception if we try to open the WordPress Backend:

Fatal error: Uncaught TypeError: ftp_nlist(): Argument #1 ($ftp) must be of type FTP\Connection, null given in /var/www/support.m3c.de/htdocs/wp-admin/includes/class-wp-filesystem-ftpext.php:438 Stack trace: #0 /var/www/support.m3c.de/htdocs/wp-admin/includes/class-wp-filesystem-ftpext.php(438): ftp_nlist() #1 /var/www/support.m3c.de/htdocs/wp-content/themes/flatbase/engine/admin/classes/class-admin-system-status.php(3485): WP_Filesystem_FTPext->exists() #2 /var/www/support.m3c.de/htdocs/wp-content/themes/flatbase/engine/admin/classes/class-admin-system-status.php(3453): Nice_Admin_System_Status->get_nice_theme_demo_packs_local() #3 /var/www/support.m3c.de/htdocs/wp-content/themes/flatbase/includes/admin/demo-packs.php(55): Nice_Admin_System_Status->get_nice_theme_demo_packs() #4 /var/www/support.m3c.de/htdocs/wp-includes/class-wp-hook.php(324): nice_theme_register_demo_packs() #5 /var/www/support.m3c.de/htdocs/wp-includes/plugin.php(205): WP_Hook->apply_filters() #6 /var/www/support.m3c.de/htdocs/wp-content/themes/flatbase/engine/admin/demo.php(82): apply_filters() #7 /var/www/support.m3c.de/htdocs/wp-content/themes/flatbase/engine/admin/demo.php(22): nice_theme_get_demo_packs() #8 /var/www/support.m3c.de/htdocs/wp-content/themes/flatbase/engine/admin/admin-pages.php(231): nice_theme_has_demo_packs() #9 /var/www/support.m3c.de/htdocs/wp-includes/class-wp-hook.php(324): nice_admin_set_pages() #10 /var/www/support.m3c.de/htdocs/wp-includes/plugin.php(205): WP_Hook->apply_filters() #11 /var/www/support.m3c.de/htdocs/wp-content/themes/flatbase/engine/admin/classes/class-admin-page.php(122): apply_filters() #12 /var/www/support.m3c.de/htdocs/wp-content/themes/flatbase/engine/admin/classes/class-admin-page.php(591): Nice_Admin_Page->set_pages() #13 /var/www/support.m3c.de/htdocs/wp-content/themes/flatbase/engine/admin/admin-page-functions.php(36): Nice_Admin_Page->__construct() #14 /var/www/support.m3c.de/htdocs/wp-content/themes/flatbase/engine/admin/init.php(113): nice_admin_page_obtain_instance() #15 /var/www/support.m3c.de/htdocs/wp-includes/class-wp-hook.php(324): nice_admin_page_init() #16 /var/www/support.m3c.de/htdocs/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters() #17 /var/www/support.m3c.de/htdocs/wp-includes/plugin.php(517): WP_Hook->do_action() #18 /var/www/support.m3c.de/htdocs/wp-settings.php(695): do_action() #19 /var/www/support.m3c.de/htdocs/wp-config.php(117): require_once(‘…’) #20 /var/www/support.m3c.de/htdocs/wp-load.php(50): require_once(‘…’) #21 /var/www/support.m3c.de/htdocs/wp-admin/admin.php(34): require_once(‘…’) #22 /var/www/support.m3c.de/htdocs/wp-admin/index.php(10): require_once(‘…’) #23 {main} thrown in /var/www/support.m3c.de/htdocs/wp-admin/includes/class-wp-filesystem-ftpext.php on line 438

What to do?

Best Regards
Johannes