diff --git a/ansible/nova.yml b/ansible/nova.yml
index 5a0c3aef3a..5e12479d7c 100644
--- a/ansible/nova.yml
+++ b/ansible/nova.yml
@@ -71,6 +71,8 @@
     - nova-cell
     - nova-cell-bootstrap
   serial: '{{ kolla_serial|default("0") }}'
+  # Fail all hosts if any of these once-per-cell tasks fails.
+  any_errors_fatal: true
   tasks:
     # * Create nova cell DBs & users
     # * Create RabbitMQ vhost & user
@@ -259,6 +261,8 @@
     - nova-online-data-migrations
     - nova-cell-online-data-migrations
   serial: '{{ kolla_serial|default("0") }}'
+  # Fail all hosts if any of these once-per-cell tasks fails.
+  any_errors_fatal: true
   tasks:
     - import_role:
         name: nova-cell
diff --git a/ansible/roles/nova-cell/tasks/discover_computes.yml b/ansible/roles/nova-cell/tasks/discover_computes.yml
index 43b2f3c1cd..49d38b6c37 100644
--- a/ansible/roles/nova-cell/tasks/discover_computes.yml
+++ b/ansible/roles/nova-cell/tasks/discover_computes.yml
@@ -19,3 +19,5 @@
 
   # Delegate to a cell conductor.
   delegate_to: "{{ groups[nova_cell_conductor_group][0] }}"
+  # Fail all hosts if any of these once-per-cell tasks fail.
+  any_errors_fatal: true