diff --git a/doc/source/upgrade.rst b/doc/source/upgrade.rst
index 91bf2591adb1..15aeeffec222 100644
--- a/doc/source/upgrade.rst
+++ b/doc/source/upgrade.rst
@@ -76,6 +76,12 @@ RPC version pinning
     are able to be upgraded.
     https://wiki.openstack.org/wiki/RpcMajorVersionUpdates
 
+    .. note::
+
+      This does not apply to cells deployments since cells does not currently
+      support rolling upgrades. It is assumed that cells deployments are
+      upgraded in lockstep so n-1 cells compatibility does not work.
+
 Online Configuration Reload
     During the upgrade, we pin new serves at the older RPC version. When all
     services are updated to use newer code, we need to unpin them so we are
diff --git a/nova/cells/manager.py b/nova/cells/manager.py
index 51091c27742a..2181cf602dc7 100644
--- a/nova/cells/manager.py
+++ b/nova/cells/manager.py
@@ -84,7 +84,10 @@ class CellsManager(manager.Manager):
                         'less testing than the rest of Nova. This may change '
                         'in the future, but current deployers should be aware '
                         'that the use of it in production right now may be '
-                        'risky.'))
+                        'risky. Also note that cells does not currently '
+                        'support rolling upgrades, it is assumed that cells '
+                        'deployments are upgraded lockstep so n-1 cells '
+                        'compatibility does not work.'))
         # Mostly for tests.
         cell_state_manager = kwargs.pop('cell_state_manager', None)
         super(CellsManager, self).__init__(service_name='cells',