diff --git a/addons/sale_stock/models/account_move.py b/addons/sale_stock/models/account_move.py
index a3632af2049..233e4882b98 100644
--- a/addons/sale_stock/models/account_move.py
+++ b/addons/sale_stock/models/account_move.py
@@ -51,9 +51,10 @@ class AccountMove(models.Model):
         last_invoice = previous_invoices[-1] if len(previous_invoices) else None
 
         # Get the incoming and outgoing sml between self.invoice_date and the previous invoice (if any).
-        self_datetime = max(self.invoice_line_ids.mapped('write_date')) if self.invoice_line_ids else None
-        last_invoice_datetime = max(last_invoice.invoice_line_ids.mapped('write_date')) if last_invoice else None
-
+        write_dates = [wd for wd in self.invoice_line_ids.mapped('write_date') if wd]
+        self_datetime = max(write_dates) if write_dates else None
+        last_write_dates = last_invoice and [wd for wd in last_invoice.invoice_line_ids.mapped('write_date') if wd]
+        last_invoice_datetime = max(last_write_dates) if last_write_dates else None
         def _filter_incoming_sml(ml):
             if ml.state == 'done' and ml.location_id.usage == 'customer' and ml.lot_id:
                 if last_invoice_datetime: