diff -r b26778f0d8a0 -r 82839782b63d src/pyams_content/features/renderer/__init__.py
--- a/src/pyams_content/features/renderer/__init__.py	Mon Aug 27 11:31:53 2018 +0200
+++ b/src/pyams_content/features/renderer/__init__.py	Mon Aug 27 11:32:07 2018 +0200
@@ -45,7 +45,7 @@
             request = check_request()
         renderer = request.registry.queryMultiAdapter((self, request), self.renderer_interface,
                                                       name=self.renderer or '')
-        if 'lang' in request.params:
+        if (renderer is not None) and ('lang' in request.params):
             renderer.language = request.params['lang']
         return renderer