diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -1691,8 +1691,8 @@
     includepats = kwargs.get(r'includepats')
     excludepats = kwargs.get(r'excludepats')
 
-    narrowstream = repo.ui.configbool('experimental.server',
-                                      'stream-narrow-clones')
+    narrowstream = repo.ui.configbool('experimental',
+                                      'server.stream-narrow-clones')
 
     if (includepats or excludepats) and not narrowstream:
         raise error.Abort(_('server does not support narrow stream clones'))
diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -610,7 +610,7 @@
 coreconfigitem('experimental', 'server.manifestdata.recommended-batch-size',
     default=100000,
 )
-coreconfigitem('experimental.server', 'stream-narrow-clones',
+coreconfigitem('experimental', 'server.stream-narrow-clones',
     default=False,
 )
 coreconfigitem('experimental', 'single-head-per-branch',