diff --git a/seahub/api2/endpoints/admin/libraries.py b/seahub/api2/endpoints/admin/libraries.py
index 697f074f0f..b44c3b67ad 100644
--- a/seahub/api2/endpoints/admin/libraries.py
+++ b/seahub/api2/endpoints/admin/libraries.py
@@ -41,7 +41,7 @@ def get_repo_info(repo):
         except Exception:
             org_repo_owner = None
 
-    owner = repo_owner or org_repo_owner
+    owner = repo_owner or org_repo_owner or ''
 
     result = {}
     result['id'] = repo.repo_id