diff --git a/addons/microsoft_calendar/models/res_users.py b/addons/microsoft_calendar/models/res_users.py
index d00125cb2ef..50a0473a45a 100644
--- a/addons/microsoft_calendar/models/res_users.py
+++ b/addons/microsoft_calendar/models/res_users.py
@@ -66,13 +66,14 @@ class User(models.Model):
                 'microsoft_calendar_token_validity': fields.Datetime.now() + timedelta(seconds=ttl),
             })
         except requests.HTTPError as error:
-            if error.response.status_code in (400, 401):  # invalid grant
+            if error.response.status_code in (400, 401):  # invalid grant or invalid client
                 # Delete refresh token and make sure it's commited
                 self.env.cr.rollback()
                 self.write({
                     'microsoft_calendar_rtoken': False,
                     'microsoft_calendar_token': False,
                     'microsoft_calendar_token_validity': False,
+                    'microsoft_calendar_sync_token': False,
                 })
                 self.env.cr.commit()
             error_key = error.response.json().get("error", "nc")