diff --git a/erpnext/stock/doctype/serial_no/serial_no.py b/erpnext/stock/doctype/serial_no/serial_no.py
index d9d1957..38291d1 100644
--- a/erpnext/stock/doctype/serial_no/serial_no.py
+++ b/erpnext/stock/doctype/serial_no/serial_no.py
@@ -342,7 +342,7 @@
 	is_stock_reco = sle.voucher_type == "Stock Reconciliation"
 	msg = None
 
-	if sr and (actual_qty < 0 or is_stock_reco) and sr.warehouse != sle.warehouse:
+	if sr and (actual_qty < 0 or is_stock_reco) and (sr.warehouse and sr.warehouse != sle.warehouse):
 		# receipt(inward) is being cancelled
 		msg = _("Cannot cancel {0} {1} as Serial No {2} does not belong to the warehouse {3}").format(
 			sle.voucher_type, doc_link, sr_link, frappe.bold(sle.warehouse))