diff --git a/addons/calendar/controllers/main.py b/addons/calendar/controllers/main.py
index 64b8812c7c2ae8293fbb563356cbe6f5285cebbe..cfecfb96345d155321b7cc79093f4dad4412ac4d 100644
--- a/addons/calendar/controllers/main.py
+++ b/addons/calendar/controllers/main.py
@@ -70,4 +70,4 @@ class CalendarController(http.Controller):
 
     @http.route('/calendar/notify_ack', type='json', auth="user")
     def notify_ack(self, type=''):
-        return request.env['res.partner']._set_calendar_last_notif_ack()
+        return request.env['res.partner'].sudo()._set_calendar_last_notif_ack()