diff -r 211472ab15c8 -r a8c1ea390400 cubicweb/utils.py
--- a/cubicweb/utils.py	Thu Mar 14 14:45:35 2019 +0100
+++ b/cubicweb/utils.py	Thu Mar 14 12:08:37 2019 +0100
@@ -42,7 +42,6 @@
 from six import text_type
 
 from logilab.mtconverter import xml_escape
-from logilab.common.deprecation import deprecated
 from logilab.common.date import ustrftime
 
 from cubicweb import Binary
@@ -442,14 +441,6 @@
         # keep main_stream's reference on req for easier text/html demoting
         req.main_stream = self
 
-    @deprecated('[3.17] there are no namespaces in html, xhtml is not served any longer')
-    def add_namespace(self, prefix, uri):
-        pass
-
-    @deprecated('[3.17] there are no namespaces in html, xhtml is not served any longer')
-    def set_namespaces(self, namespaces):
-        pass
-
     def add_htmlattr(self, attrname, attrvalue):
         self._htmlattrs.append( (attrname, attrvalue) )