Remove 'warn' - its no longer supported.

roles/common/tasks/caching-nameserver.yml

@@ -15,14 +15,11 @@
   tags:
     - apt-caching-nameserver
 
-
-- name: (caching-nameserver.yml) dpkg --configure
-  command: >
-    dpkg --configure -a
-  args:
-    warn: false
-  changed_when: _dpkg_configure.stdout_lines | length
+- name: (caching-nameserver.yml) Configure any half-installed packages 'dpkg --configure -a'
+  ansible.builtin.command: dpkg --configure -a
   register: _dpkg_configure
+  changed_when: (_dpkg_configure.stdout | default('')) | length > 0
+  failed_when: _dpkg_configure.rc != 0
   when:
     - ansible_distribution == "Debian"
     - apt_update|bool