diff --git a/app/service/invoice/InvoiceIssuanceService.php b/app/service/invoice/InvoiceIssuanceService.php
index 0907136..97aed8f 100644
--- a/app/service/invoice/InvoiceIssuanceService.php
+++ b/app/service/invoice/InvoiceIssuanceService.php
@@ -53,7 +53,7 @@ class InvoiceIssuanceService
                                $item->head_type  = InvoiceHead::$typeArr[$InvoiceHead['type']];
                                $item->head_title = $InvoiceHead['title'];
                            }
-                           $item->project_id = InvoiceIssuance::$projectArr[$item->project_id];
+                           $item->project_id = InvoiceIssuance::$projectArr[$item->project_id] ?? '';
                            $item->status     = InvoiceIssuance::$statusArr[$item->status];
                        });
         return $data->toArray();