diff --git a/kallithea/lib/vcs/backends/hg/repository.py b/kallithea/lib/vcs/backends/hg/repository.py
--- a/kallithea/lib/vcs/backends/hg/repository.py
+++ b/kallithea/lib/vcs/backends/hg/repository.py
@@ -212,7 +212,7 @@ class MercurialRepository(BaseRepository
         local = False
 
         try:
-            mercurial.tags.tag(self._repo, safe_bytes(name), mercurial.commands.nullid, safe_bytes(message), local, safe_bytes(user), date)
+            mercurial.tags.tag(self._repo, safe_bytes(name), mercurial.node.nullid, safe_bytes(message), local, safe_bytes(user), date)
             self.tags = self._get_tags()
         except mercurial.error.Abort as e:
             raise RepositoryError(e.args[0])