diff --git a/addons/website/models/ir_http.py b/addons/website/models/ir_http.py
index 785d794e9ca..65136703c8a 100644
--- a/addons/website/models/ir_http.py
+++ b/addons/website/models/ir_http.py
@@ -208,6 +208,10 @@ class Http(models.AbstractModel):
 
             if isinstance(exception, QWebException):
                 values.update(qweb_exception=exception)
+
+                # retro compatibility to remove in 12.2
+                exception.qweb = dict(message=exception.message, expression=exception.html)
+
                 if type(exception.error) == odoo.exceptions.AccessError:
                     code = 403