diff --git a/lib/charms/grafana_agent/v0/cos_agent.py b/lib/charms/grafana_agent/v0/cos_agent.py
index cc4da25..3aed66a 100644
--- a/lib/charms/grafana_agent/v0/cos_agent.py
+++ b/lib/charms/grafana_agent/v0/cos_agent.py
@@ -64,7 +64,8 @@ def __init__(
 
 - `dashboard_dirs`: List of directories where the dashboards are stored in the Charmed Operator.
 
-- `refresh_events`: List of events on which to refresh relation data.
+- `refresh_events`: List of events on which to refresh relation data. If no events is passed, the
+    relation data will be refreshed on config-changed and charm upgrade.
 
 - `tracing_protocols`: List of requested tracing protocols that the charm requires to send traces.
 
@@ -175,7 +176,8 @@ def __init__(self, *args):
   `cos_agent` interface.
   The default value of this argument is "cos-agent".
 
-- `refresh_events`: List of events on which to refresh relation data.
+- `refresh_events`: List of events on which to refresh relation data. If no events is passed, the
+    relation data will be refreshed on config-changed and charm upgrade.
 
 
 ### Example 1 - Minimal instrumentation:
@@ -653,7 +655,10 @@ def __init__(
         self._recursive = recurse_rules_dirs
         self._log_slots = log_slots or []
         self._dashboard_dirs = dashboard_dirs
-        self._refresh_events = refresh_events or [self._charm.on.config_changed]
+        self._refresh_events = refresh_events or [
+            self._charm.on.config_changed,
+            self._charm.on.upgrade_charm,
+        ]
         self._tracing_protocols = tracing_protocols
         self._is_single_endpoint = charm.meta.relations[relation_name].limit == 1
 
@@ -895,7 +900,10 @@ def __init__(
         self._charm = charm
         self._relation_name = relation_name
         self._peer_relation_name = peer_relation_name
-        self._refresh_events = refresh_events or [self._charm.on.config_changed]
+        self._refresh_events = refresh_events or [
+            self._charm.on.config_changed,
+            self._charm.on.upgrade_charm,
+        ]
 
         events = self._charm.on[relation_name]
         self.framework.observe(
diff --git a/tests/scenario/test_machine_charm/test_cos_agent_e2e.py b/tests/scenario/test_machine_charm/test_cos_agent_e2e.py
index abf53fc..5dba3c2 100644
--- a/tests/scenario/test_machine_charm/test_cos_agent_e2e.py
+++ b/tests/scenario/test_machine_charm/test_cos_agent_e2e.py
@@ -53,9 +53,11 @@ def placeholder_cfg_path(tmp_path):
 
 @pytest.fixture(autouse=True)
 def patch_all(placeholder_cfg_path):
-    with patch("subprocess.run", MagicMock()), patch(
-        "grafana_agent.CONFIG_PATH", placeholder_cfg_path
-    ), patch("socket.getfqdn", return_value="localhost"):
+    with (
+        patch("subprocess.run", MagicMock()),
+        patch("grafana_agent.CONFIG_PATH", placeholder_cfg_path),
+        patch("socket.getfqdn", return_value="localhost"),
+    ):
         yield
 
 
diff --git a/tests/scenario/test_machine_charm/test_scrape_configs.py b/tests/scenario/test_machine_charm/test_scrape_configs.py
index 075ab64..6529224 100644
--- a/tests/scenario/test_machine_charm/test_scrape_configs.py
+++ b/tests/scenario/test_machine_charm/test_scrape_configs.py
@@ -65,9 +65,11 @@ def mock_write(_, path, text):
 
     my_uuid = str(uuid.uuid4())
 
-    with patch("charms.operator_libs_linux.v2.snap.SnapCache"), patch(
-        "charm.GrafanaAgentMachineCharm.write_file", new=mock_write
-    ), patch("charm.GrafanaAgentMachineCharm.is_ready", return_value=True):
+    with (
+        patch("charms.operator_libs_linux.v2.snap.SnapCache"),
+        patch("charm.GrafanaAgentMachineCharm.write_file", new=mock_write),
+        patch("charm.GrafanaAgentMachineCharm.is_ready", return_value=True),
+    ):
         state = State(
             relations=[cos_relation, loki_relation, PeerRelation("peers")],
             model=Model(name="my-model", uuid=my_uuid),
diff --git a/tests/scenario/test_start_statuses.py b/tests/scenario/test_start_statuses.py
index c3235aa..f7fdc66 100644
--- a/tests/scenario/test_start_statuses.py
+++ b/tests/scenario/test_start_statuses.py
@@ -31,8 +31,9 @@ def _subp_run_mock(*a, **kw):
 
 @pytest.fixture(autouse=True)
 def patch_all(placeholder_cfg_path):
-    with patch("subprocess.run", _subp_run_mock), patch(
-        "grafana_agent.CONFIG_PATH", placeholder_cfg_path
+    with (
+        patch("subprocess.run", _subp_run_mock),
+        patch("grafana_agent.CONFIG_PATH", placeholder_cfg_path),
     ):
         yield