diff --git a/cou/apps/base.py b/cou/apps/base.py
index 05a4ff53..29232bc5 100644
--- a/cou/apps/base.py
+++ b/cou/apps/base.py
@@ -147,7 +147,7 @@ def __repr__(self) -> str:
     def apt_source_codename(self) -> OpenStackRelease:
         """Identify the OpenStack release set on "openstack-origin" or "source" config.
 
-        :raises ApplicationError: When origin setting is not valid.
+        :raises ApplicationError: When origin setting or series are not valid.
         :return: OpenStackRelease object.
         :rtype: OpenStackRelease
         """
@@ -160,6 +160,8 @@ def apt_source_codename(self) -> OpenStackRelease:
 
         if self.os_origin == "distro":
             # find the OpenStack release based on ubuntu series
+            if self.series not in DISTRO_TO_OPENSTACK_MAPPING:
+                raise ApplicationError(f"Series '{self.series}' is not supported by COU.")
             return OpenStackRelease(DISTRO_TO_OPENSTACK_MAPPING[self.series])
 
         # probably because user set a ppa or a url
@@ -205,9 +207,16 @@ def channel_codename(self) -> OpenStackRelease:
     def current_os_release(self) -> OpenStackRelease:
         """Current OpenStack Release of the application.
 
+        Applications that are colocated in a same machine will upgrade all the packages in the
+        machine during an upgrade. This means that when upgrading a application X, the application
+        Y colocated with it also upgrades its packages. To ensure to change the 'source' or
+        'openstack-origin' and run all the upgrade steps necessary, it's necessary to include the
+        OpenStack release set in the application configuration.
         :return: OpenStackRelease object
         :rtype: OpenStackRelease
         """
+        if self.os_origin:
+            return min(list(self.os_release_units.keys()) + [self.apt_source_codename])
         return min(self.os_release_units.keys())
 
     @property
diff --git a/cou/steps/plan.py b/cou/steps/plan.py
index dabd622f..f3284797 100644
--- a/cou/steps/plan.py
+++ b/cou/steps/plan.py
@@ -400,7 +400,7 @@ def _get_post_upgrade_steps(analysis_result: Analysis, args: CLIargs) -> list[Po
     """
     steps = []
     if args.upgrade_group in {DATA_PLANE, None}:
-        steps.extend(_get_ceph_mon_post_upgrade_steps(analysis_result.apps_data_plane))
+        steps.extend(_get_ceph_mon_post_upgrade_steps(analysis_result.apps_control_plane))
 
     return steps
 
@@ -415,7 +415,11 @@ def _get_ceph_mon_post_upgrade_steps(apps: list[OpenStackApplication]) -> list[P
     """
     ceph_mons_apps = [app for app in apps if isinstance(app, CephMon)]
 
-    steps = []
+    steps: list[PostUpgradeStep] = []
+    if not ceph_mons_apps:
+        logger.warning("There is no ceph-mon application. Is this a valid OpenStack cloud?")
+        return steps
+
     for app in ceph_mons_apps:
         unit = list(app.units.values())[0]  # getting the first unit, since we don't care which one
         steps.append(
diff --git a/tests/mocked_plans/sample_plans/018346c5-f95c-46df-a34e-9a78bdec0018.yaml b/tests/mocked_plans/sample_plans/018346c5-f95c-46df-a34e-9a78bdec0018.yaml
index e634e0cd..9d884d1b 100644
--- a/tests/mocked_plans/sample_plans/018346c5-f95c-46df-a34e-9a78bdec0018.yaml
+++ b/tests/mocked_plans/sample_plans/018346c5-f95c-46df-a34e-9a78bdec0018.yaml
@@ -497,6 +497,7 @@ plan: |
                 Upgrade 'cinder-lvm-slow' to the new channel: 'victoria/stable'
             Upgrade plan for 'cinder-volume-mysql-router' to 'victoria'
                 Refresh 'cinder-volume-mysql-router' to the latest revision of '8.0/stable'
+        Ensure that the 'require-osd-release' option in 'ceph-mon' matches the 'ceph-osd' version
 
 
 applications:
diff --git a/tests/mocked_plans/sample_plans/9eb9af6a-b919-4cf9-8f2f-9df16a1556be.yaml b/tests/mocked_plans/sample_plans/9eb9af6a-b919-4cf9-8f2f-9df16a1556be.yaml
index 53d4b3a0..5a004291 100644
--- a/tests/mocked_plans/sample_plans/9eb9af6a-b919-4cf9-8f2f-9df16a1556be.yaml
+++ b/tests/mocked_plans/sample_plans/9eb9af6a-b919-4cf9-8f2f-9df16a1556be.yaml
@@ -433,6 +433,7 @@ plan: |
             Upgrade plan for 'ovn-chassis' to 'victoria'
                 WARNING: Changing 'ovn-chassis' channel from latest/stable to 22.03/stable. This may be a charm downgrade, which is generally not supported.
                 Upgrade 'ovn-chassis' to the new channel: '22.03/stable'
+        Ensure that the 'require-osd-release' option in 'ceph-mon' matches the 'ceph-osd' version
 
 applications:
   rabbitmq-server:
diff --git a/tests/unit/apps/test_auxiliary.py b/tests/unit/apps/test_auxiliary.py
index e612c3d7..f2a5579f 100644
--- a/tests/unit/apps/test_auxiliary.py
+++ b/tests/unit/apps/test_auxiliary.py
@@ -72,7 +72,11 @@ def test_auxiliary_app(model):
     assert app.apt_source_codename == "ussuri"
     assert app.channel_codename == "yoga"
     assert app.is_subordinate is False
-    assert app.current_os_release == "yoga"
+
+    # the workload version of units are considered as yoga
+    assert min(app.os_release_units.keys()) == "yoga"
+    # application is considered as ussuri because the source is pointing to it
+    assert app.current_os_release == "ussuri"
 
 
 def test_auxiliary_app_cs(model):
@@ -104,7 +108,10 @@ def test_auxiliary_app_cs(model):
     assert app.os_origin == "distro"
     assert app.apt_source_codename == "ussuri"
     assert app.channel_codename == "ussuri"
-    assert app.current_os_release == "yoga"
+    # the workload version of units are considered as yoga
+    assert min(app.os_release_units.keys()) == "yoga"
+    # application is considered as ussuri because the source is pointing to it
+    assert app.current_os_release == "ussuri"
 
 
 def test_auxiliary_upgrade_plan_ussuri_to_victoria_change_channel(model):
@@ -397,12 +404,7 @@ def test_auxiliary_raise_error_unknown_series(model):
     """Test auxiliary application with unknown series."""
     series = "foo"
     channel = "3.8/stable"
-    exp_msg = (
-        f"Channel: {channel} for charm 'rabbitmq-server' on series '{series}' is not supported by "
-        "COU. Please take a look at the documentation: "
-        "https://docs.openstack.org/charm-guide/latest/project/charm-delivery.html "
-        "to see if you are using the right track."
-    )
+    exp_msg = "Series 'foo' is not supported by COU."
     machines = {"0": MagicMock(spec_set=Machine)}
     app = RabbitMQServer(
         name="rabbitmq-server",
@@ -818,7 +820,7 @@ def test_ovn_principal(model):
     assert app.os_origin == "distro"
     assert app.apt_source_codename == "ussuri"
     assert app.channel_codename == "yoga"
-    assert app.current_os_release == "yoga"
+    assert app.current_os_release == "ussuri"
     assert app.is_subordinate is False
 
 
diff --git a/tests/unit/steps/test_analyze.py b/tests/unit/steps/test_analyze.py
index 0a9f8849..f383bb5c 100644
--- a/tests/unit/steps/test_analyze.py
+++ b/tests/unit/steps/test_analyze.py
@@ -451,7 +451,7 @@ async def test_analysis_detect_current_cloud_series_different_series(model):
         can_upgrade_to="ussuri/stable",
         charm="cinder",
         channel="ussuri/stable",
-        config={"source": {"value": "distro"}},
+        config={"source": {"value": "cloud:bionic-ussuri"}},
         machines=machines,
         model=model,
         origin="ch",
diff --git a/tests/unit/steps/test_plan.py b/tests/unit/steps/test_plan.py
index 1c5c59b3..0906ee9a 100644
--- a/tests/unit/steps/test_plan.py
+++ b/tests/unit/steps/test_plan.py
@@ -1063,7 +1063,7 @@ def test_get_post_upgrade_steps_ceph_mon(mock_get_ceph_mon_post_upgrade_steps, u
     pre_upgrade_steps = cou_plan._get_post_upgrade_steps(analysis_result, args)
 
     assert pre_upgrade_steps == mock_get_ceph_mon_post_upgrade_steps.return_value
-    mock_get_ceph_mon_post_upgrade_steps.assert_called_with(analysis_result.apps_data_plane)
+    mock_get_ceph_mon_post_upgrade_steps.assert_called_with(analysis_result.apps_control_plane)
 
 
 def test_get_ceph_mon_post_upgrade_steps_zero(model):