diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -466,9 +466,6 @@
             for name, bmrev in repo._bookmarks.iteritems():
                 if matcher(name):
                     matchrevs.add(bmrev)
-            if not matchrevs:
-                raise error.RepoLookupError(_("no bookmarks exist"
-                                              " that match '%s'") % pattern)
             for bmrev in matchrevs:
                 bms.add(repo[bmrev].rev())
     else:
@@ -1330,9 +1327,6 @@
         for name, ns in repo.names.iteritems():
             if matcher(name):
                 namespaces.add(ns)
-        if not namespaces:
-            raise error.RepoLookupError(_("no namespace exists"
-                                          " that match '%s'") % pattern)
 
     names = set()
     for ns in namespaces:
diff --git a/tests/test-bookmarks.t b/tests/test-bookmarks.t
--- a/tests/test-bookmarks.t
+++ b/tests/test-bookmarks.t
@@ -202,8 +202,6 @@
   abort: bookmark 'unknown' does not exist!
   [255]
   $ hg log -r 'bookmark("re:unknown")'
-  abort: no bookmarks exist that match 'unknown'!
-  [255]
   $ hg log -r 'present(bookmark("literal:unknown"))'
   $ hg log -r 'present(bookmark("re:unknown"))'
 
diff --git a/tests/test-revset2.t b/tests/test-revset2.t
--- a/tests/test-revset2.t
+++ b/tests/test-revset2.t
@@ -669,8 +669,6 @@
   abort: namespace 'unknown' does not exist!
   [255]
   $ log 'named("re:unknown")'
-  abort: no namespace exists that match 'unknown'!
-  [255]
   $ log 'present(named("unknown"))'
   $ log 'present(named("re:unknown"))'