Fatal error: Uncaught Error: Call to a member function get_results() on string in /home/www/mysite.com/myfolder/wp-content/plugins/wp-w3all-phpbb-integration/class.wp.w3all-phpbb.php:1785 Stack trace: #0 /home/www/mysite.com/myfolder/wp-content/plugins/wp-w3all-phpbb-integration/class.wp.w3all-phpbb.php(1864): WP_w3all_phpbb::wp_w3all_get_phpbb_user_info('valeriats') #1 /home/www/mysite.com/myfolder/wp-content/plugins/wp-w3all-phpbb-integration/wp_w3all.php(1143): WP_w3all_phpbb::wp_w3all_phpbb_delete_user_signup(3783) #2 /home/www/mysite.com/myfolder/wp-includes/class-wp-hook.php(309): w3all_wpmu_delete_user(3783) #3 /home/www/mysite.com/myfolder/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters('', Array) #4 /home/www/mysite.com/myfolder/wp-includes/plugin.php(474): WP_Hook->do_action(Array) #5 /home/www/mysite.com/myfolder/wp-admin/includes/ms.php(173): do_action('wpmu_delete_use...', 3783, Object(WP_User)) #6 /home/www/mysite.com/myfolder/wp-admi in /home/www/mysite.com/myfolder/wp-content/plugins/wp-w3all-phpbb-integration/class.wp.w3all-phpbb.php on line 1785
I tested with no errors (again just now) both subsite and main deletion.
I will try to reverse how it can come out your side due to some plugin?
Let see the error stack again...
Fatal error: Uncaught Error: Call to a member function get_results() on string in /home/www/mysite.com/myfolder/wp-content/plugins/wp-w3all-phpbb-integration/class.wp.w3all-phpbb.php:1788 Stack trace: #0 /home/www/mysite.com/myfolder/wp-content/plugins/wp-w3all-phpbb-integration/class.wp.w3all-phpbb.php(1871): WP_w3all_phpbb::wp_w3all_get_phpbb_user_info('spammer@gm...') #1 /home/www/mysite.com/myfolder/wp-content/plugins/wp-w3all-phpbb-integration/wp_w3all.php(1143): WP_w3all_phpbb::wp_w3all_phpbb_delete_user_signup(3849) #2 /home/www/mysite.com/myfolder/wp-includes/class-wp-hook.php(309): w3all_wpmu_delete_user(3849) #3 /home/www/mysite.com/myfolder/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters('', Array) #4 /home/www/mysite.com/myfolder/wp-includes/plugin.php(474): WP_Hook->do_action(Array) #5 /home/www/mysite.com/myfolder/wp-admin/includes/ms.php(173): do_action('wpmu_delete_use...', 3849, Object(WP_User)) #6 /home/www/mysite.com/myfolde in /home/www/mysite.com/myfolder/plugins/wp-w3all-phpbb-integration/class.wp.w3all-phpbb.php on line 1788
Very strange because function's stack as you report, should be clean.
At moment i have try any possibility and all work as expected. Except the code review, it has been tested into any default WP install with no error. I am sorry, it is really not clear how you can get this.