diff --git a/sushy_tools/emulator/main.py b/sushy_tools/emulator/main.py
index bfc51a37..3d68da21 100755
--- a/sushy_tools/emulator/main.py
+++ b/sushy_tools/emulator/main.py
@@ -405,8 +405,15 @@ def manager_resource(identity):
     elif flask.request.method == "PATCH":
         if app.feature_set != "full":
             raise error.MethodNotAllowed("PATCH not supported in minimum mode")
+        try:
+            data = flask.request.get_json()
+        except wz_exc.BadRequest:
+            app.logger.error(
+                "PATCH method missing in /Managers/%s due to invalid JSON",
+                identity
+            )
+            raise error.BadRequest("Request must be a valid JSON")
 
-        data = flask.request.get_json(force=True)
         new_datetime = data.get("DateTime")
         new_offset = data.get("DateTimeLocalOffset")
 
diff --git a/sushy_tools/tests/unit/emulator/test_main.py b/sushy_tools/tests/unit/emulator/test_main.py
index 7d946384..e399c9d2 100644
--- a/sushy_tools/tests/unit/emulator/test_main.py
+++ b/sushy_tools/tests/unit/emulator/test_main.py
@@ -238,6 +238,33 @@ class ManagersTestCase(EmulatorTestCase):
         self.assertEqual({'@odata.id': '/redfish/v1/Systems/xxx/VirtualMedia'},
                          response.json['VirtualMedia'])
 
+    @patch_resource('managers')
+    def test_manager_resource_patch_valid_json(self, managers_mock):
+        managers_mock = managers_mock.return_value
+        managers_mock.set_datetime.return_value = None
+
+        payload = {
+            "DateTime": "2025-07-14T11:30:00+00:00",
+            "DateTimeLocalOffset": "+00:00"}
+
+        response = self.app.patch(
+            '/redfish/v1/Managers/xxxx-yyyy-zzzz',
+            json=payload)
+
+        self.assertEqual(204, response.status_code)
+
+    @patch_resource('managers')
+    def test_manager_resource_patch_invalid_json(self, managers_mock):
+        managers_mock = managers_mock.return_value
+        managers_mock.set_datetime.return_value = None
+
+        response = self.app.patch(
+            '/redfish/v1/Managers/xxxx-yyyy-zzzz',
+            data='not-json',
+            content_type='application/json')
+
+        self.assertEqual(400, response.status_code)
+
     @patch_resource('managers')
     def test_manager_resource_get_reduced_feature_set(self, managers_mock):
         self.set_feature_set("vmedia")