models/service_order.py

@@ -995,8 +995,11 @@ class service_order(osv.osv):
 
         res = True
         for order in self.browse(cr, uid, ids, context):
+            inv_ids = []
             for sale in order.sale_order_ids:
-                if not sale.invoiced and sale.state != 'cancel':
+                inv_ids += [invoice for invoice in sale.invoice_ids]
+                invoices_ok = all([invoice.state in ('paid', 'cancel') for invoice in inv_ids])
+                if not invoices_ok and sale.state != 'cancel':
                     raise osv.except_osv(
                         _("Cannot finish"),
                         _("All quotation should be paid or cancelled"))