Update set_delivery_date_in_so_item.py
diff --git a/erpnext/patches/v8_1/set_delivery_date_in_so_item.py b/erpnext/patches/v8_1/set_delivery_date_in_so_item.py
index 963b82a..aa5cbc5 100644
--- a/erpnext/patches/v8_1/set_delivery_date_in_so_item.py
+++ b/erpnext/patches/v8_1/set_delivery_date_in_so_item.py
@@ -18,4 +18,6 @@
and so.order_type = 'Sales'
and (so_item.delivery_date is null or so_item.delivery_date = ''
or so_item.delivery_date = '0000-00-00')
- """)
\ No newline at end of file
+ and (so.delivery_date is not null and so.delivery_date != ''
+ and so.delivery_date != '0000-00-00')
+ """)