ok

src/Helpers/ExcelHelper.php

@@ -54,7 +54,9 @@ class ExcelHelper
         foreach ($data as $item) {
             $calc++;
             if ($limit == $calc) {
-                ob_flush();
+                if (ob_get_level() > 0) {
+                    ob_flush();
+                }
                 flush();
                 $calc = 0;
             }