diff --git a/frappe/model/base_document.py b/frappe/model/base_document.py
index 1cafc08944..ebfe364b60 100644
--- a/frappe/model/base_document.py
+++ b/frappe/model/base_document.py
@@ -962,9 +962,7 @@ class BaseDocument:
 			if not docname:
 				continue
 
-			assert isinstance(docname, str | int) or (
-				isinstance(docname, list | tuple | set) and len(docname) == 1
-			), f"Unexpected value for field {df.fieldname}: {docname}"
+			assert isinstance(docname, str | int), f"Unexpected value for field {df.fieldname}: {docname}"
 
 			if df.fieldtype == "Link":
 				doctype = df.options