++ b/addons/crm/models/crm_lead.py
@@ -213,7 +213,10 @@ class Lead(models.Model):
     @api.onchange('stage_id')
     def _onchange_stage_id(self):
         values = self._onchange_stage_id_values(self.stage_id.id)
-        self.update(values)
+        action = self.env.ref('crm.crm_lead_lost_action').read()[0]
+        return {
+            'action': action
+        }

     def _onchange_partner_id_values(self, partner_id):
         """ returns the new values when partner_id has changed """
diff --git a/addons/web/static/src/js/views/basic/basic_model.js b/addons/web/static/src/js/views/basic/basic_model.js
index cb48e09fe98..b3ea29ed198 100644
--- a/addons/web/static/src/js/views/basic/basic_model.js
+++ b/addons/web/static/src/js/views/basic/basic_model.js
@@ -3753,6 +3753,9 @@ var BasicModel = AbstractModel.extend({
                     // ignore the onchange.
                     return;
                 }
+                if (result.action) {
+                    self.do_action(result.action);
+                }
                 if (result.warning) {
                     self.trigger_up('warning', {
                         message: result.warning.message,
diff --git a/odoo/models.py b/odoo/models.py
index a69ee54781f..53103697f69 100644
--- a/odoo/models.py
+++ b/odoo/models.py
@@ -5345,6 +5345,8 @@ class BaseModel(MetaModel('DummyModel', (object,), {'_register': False})):
                     res['warning'].get('title') or _("Warning"),
                     res['warning'].get('message') or "",
                 ))
+            if res.get('action'):
+                result['action'] = res['action']

         if onchange in ("1", "true"):
             for method in self._onchange_methods.get(field_name, ()):