fix

common/modules/bids/controllers/BidAdminController.php

@@ -115,10 +115,13 @@ class BidAdminController extends AdminController
         $model = BidFile::findOne($id);
         
         if($model) {
-            return Yii::$app->response->sendFile(BidFile::path() . $model->filename, $model->filename);
-        } else {
-            throw new NotFoundHttpException('The requested page does not exist.');
+            $path = BidFile::path() . $model->filename;
+            if(file_exists($path)) {
+                return Yii::$app->response->sendFile(BidFile::path() . $model->filename, $model->filename);
+            }
         }
+
+        throw new NotFoundHttpException('The requested page does not exist.');
     }
 
     /**