diff --git a/sphinx/directives/__init__.py b/sphinx/directives/__init__.py
index c45232c92e7..4c92af67d9d 100644
--- a/sphinx/directives/__init__.py
+++ b/sphinx/directives/__init__.py
@@ -296,7 +296,7 @@ def run(self) -> list[Node]:
             'object-description-transform', self.domain, self.objtype, content_node
         )
         DocFieldTransformer(self).transform_all(content_node)
-        self.env.temp_data['object'] = None
+        self.env.temp_data['object'] = ''
         self.after_content()
 
         if node['no-typesetting']:
diff --git a/sphinx/domains/changeset.py b/sphinx/domains/changeset.py
index a27c5f571a8..abf622d5bb8 100644
--- a/sphinx/domains/changeset.py
+++ b/sphinx/domains/changeset.py
@@ -41,7 +41,7 @@ class ChangeSet(NamedTuple):
     docname: str
     lineno: int
     module: str | None
-    descname: str | None
+    descname: str
     content: str
 
 
@@ -123,7 +123,7 @@ def changesets(self) -> dict[str, list[ChangeSet]]:
     def note_changeset(self, node: addnodes.versionmodified) -> None:
         version = node['version']
         module = self.env.ref_context.get('py:module')
-        objname = self.env.temp_data.get('object')
+        objname = self.env.temp_data.get('object', '')
         changeset = ChangeSet(node['type'], self.env.docname, node.line,  # type: ignore[arg-type]
                               module, objname, node.astext())
         self.changesets.setdefault(version, []).append(changeset)