Thank you for the help. Hereunder is the content of the debug log file.
WordPress database error Thread stack overrun: 8640 bytes used of a 131072 byte stack, and 128000 bytes needed. Use ‘mysqld –thread_stack=#’ to specify a bigger stack. for query INSERT INTO wbk_appointments
(name
, email
, phone
, description
, service_id
, time
, day
, duration
, extra
, quantity
, time_offset
, attachment
) VALUES (‘xx’, ‘[email protected]’, ‘(111) 111-1111’, ‘jaslkjdlksa’, 2, 1586336400, 1586304000, 120, ‘[]’, 1, -480, ”) made by do_action(‘wp_ajax_wbk_book’), WP_Hook->do_action, WP_Hook->apply_filters, WBK_Ajax_Controller->ajaxBook, WBK_Appointment->add