--- a/mercurial/hgweb.py
+++ b/mercurial/hgweb.py
@@ -889,7 +889,7 @@ class hgweb(object):
         else:
             req.write(self.t("error"))
 
-def create_server(repo):
+def create_server(ui, repo):
     use_threads = True
 
     def openlog(opt, default):
@@ -897,12 +897,12 @@ def create_server(repo):
             return open(opt, 'w')
         return default
 
-    address = repo.ui.config("web", "address", "")
-    port = int(repo.ui.config("web", "port", 8000))
-    use_ipv6 = repo.ui.configbool("web", "ipv6")
-    webdir_conf = repo.ui.config("web", "webdir_conf")
-    accesslog = openlog(repo.ui.config("web", "accesslog", "-"), sys.stdout)
-    errorlog = openlog(repo.ui.config("web", "errorlog", "-"), sys.stderr)
+    address = ui.config("web", "address", "")
+    port = int(ui.config("web", "port", 8000))
+    use_ipv6 = ui.configbool("web", "ipv6")
+    webdir_conf = ui.config("web", "webdir_conf")
+    accesslog = openlog(ui.config("web", "accesslog", "-"), sys.stdout)
+    errorlog = openlog(ui.config("web", "errorlog", "-"), sys.stderr)
 
     if use_threads:
         try:
@@ -988,8 +988,10 @@ def create_server(repo):
 
             if webdir_conf:
                 hgwebobj = hgwebdir(webdir_conf)
+            elif repo is not None:
+                hgwebobj = hgweb(repo.__class__(repo.ui, repo.origroot))
             else:
-                hgwebobj = hgweb(repo.__class__(repo.ui, repo.origroot))
+                raise hg.RepoError(_('no repo found'))
             hgwebobj.run(req)