diff --git a/doc/source/reference/notifications.rst b/doc/source/reference/notifications.rst
index 79b85fee3a..52d7a0eeb5 100644
--- a/doc/source/reference/notifications.rst
+++ b/doc/source/reference/notifications.rst
@@ -113,9 +113,7 @@ notification payload:
 
 There is a Nova configuration parameter
 :oslo.config:option:`notifications.notification_format`
-that can be used to specify which notifications are emitted by Nova. The
-possible values are ``unversioned``, ``versioned``, ``both`` and the default
-value is ``both``.
+that can be used to specify which notifications are emitted by Nova.
 
 The versioned notifications are emitted to a different topic than the legacy
 notifications. By default they are emitted to 'versioned_notifications' but it
diff --git a/nova/conf/notifications.py b/nova/conf/notifications.py
index edde86880a..a5946ddb3c 100644
--- a/nova/conf/notifications.py
+++ b/nova/conf/notifications.py
@@ -57,7 +57,7 @@ additional information on notifications.
         help="Default notification level for outgoing notifications."),
     cfg.StrOpt(
         'notification_format',
-        default='both',
+        default='unversioned',
         choices=[
             ('both', 'Both the legacy unversioned and the new versioned '
              'notifications are emitted'),
@@ -67,12 +67,14 @@ additional information on notifications.
         ],
         deprecated_group='DEFAULT',
         help="""
-Specifies which notification format shall be used by nova.
+Specifies which notification format shall be emitted by nova.
 
-The default value is fine for most deployments and rarely needs to be changed.
-This value can be set to 'versioned' once the infrastructure moves closer to
-consuming the newer format of notifications. After this occurs, this option
-will be removed.
+The versioned notification interface are in feature parity with the legacy
+interface and the versioned interface is actively developed so new consumers
+should used the versioned interface.
+
+However, the legacy interface is heavily used by ceilometer and other mature
+OpenStack components so it remains the default.
 
 Note that notifications can be completely disabled by setting ``driver=noop``
 in the ``[oslo_messaging_notifications]`` group.
diff --git a/nova/tests/unit/conf_fixture.py b/nova/tests/unit/conf_fixture.py
index c199c649b0..6e4f5a8ee2 100644
--- a/nova/tests/unit/conf_fixture.py
+++ b/nova/tests/unit/conf_fixture.py
@@ -77,6 +77,10 @@ class ConfFixture(config_fixture.Config):
         # tests.
         self.conf.set_default('keep_alive', False, group="wsgi")
 
+        # many tests synchronizes on the reception of versioned notifications
+        self.conf.set_default(
+            'notification_format', "both", group="notifications")
+
         config.parse_args([], default_config_files=[], configure_db=False,
                           init_rpc=False)
         policy_opts.set_defaults(self.conf)
diff --git a/releasenotes/notes/unversioned-as-default-notification_format-f149db44b319aa07.yaml b/releasenotes/notes/unversioned-as-default-notification_format-f149db44b319aa07.yaml
new file mode 100644
index 0000000000..18b088fa69
--- /dev/null
+++ b/releasenotes/notes/unversioned-as-default-notification_format-f149db44b319aa07.yaml
@@ -0,0 +1,11 @@
+---
+upgrade:
+  - |
+    To resolve `bug 1805659`_ the default value of
+    ``[notifications]/notification_format`` is changed from ``both`` to
+    ``unversioned``. For more information see the `documentation of the config
+    option`_. If you are using versioned notifications, you will need to adjust
+    your config to ``versioned``"
+
+    .. _`bug 1805659`: https://bugs.launchpad.net/nova/+bug/1805659
+    .. _`documentation of the config option`: https://docs.openstack.org/nova/latest/configuration/config.html#notifications.notification_format