diff -r 211472ab15c8 -r a8c1ea390400 cubicweb/pyramid/core.py
--- a/cubicweb/pyramid/core.py	Thu Mar 14 14:45:35 2019 +0100
+++ b/cubicweb/pyramid/core.py	Thu Mar 14 12:08:37 2019 +0100
@@ -177,15 +177,6 @@
                 val = (val.filename, val.file)
             if param == '_cwmsgid':
                 self.set_message_id(val)
-            elif param == '__message':
-                warn('[3.13] __message in request parameter is deprecated '
-                     '(may only be given to .build_url). Seeing this message '
-                     'usualy means your application hold some <form> where '
-                     'you should replace use of __message hidden input by '
-                     'form.set_message, so new _cwmsgid mechanism is properly '
-                     'used',
-                     DeprecationWarning)
-                self.set_message(val)
             else:
                 self.form[param] = val