diff --git a/openedx/core/djangoapps/content_libraries/api.py b/openedx/core/djangoapps/content_libraries/api.py
index 87325301866b..e6a0500c21ff 100644
--- a/openedx/core/djangoapps/content_libraries/api.py
+++ b/openedx/core/djangoapps/content_libraries/api.py
@@ -219,7 +219,7 @@ class LibraryXBlockMetadata:
     display_name = attr.ib("")
     last_published = attr.ib(default=None, type=datetime)
     last_draft_created = attr.ib(default=None, type=datetime)
-    last_draft_created_by = attr.ib(default=None, type=datetime)
+    last_draft_created_by = attr.ib("")
     published_by = attr.ib("")
     has_unpublished_changes = attr.ib(False)
     tags_count = attr.ib(0)