Update Samples.php

Declare module namespace before template path

Author: mageprince

app/code/Magento/Downloadable/Block/Adminhtml/Catalog/Product/Edit/Tab/Downloadable/Samples.php

@@ -22,7 +22,7 @@ class Samples extends \Magento\Backend\Block\Widget
     /**
      * @var string
      */
-    protected $_template = 'product/edit/downloadable/samples.phtml';
+    protected $_template = 'Magento_Downloadable::product/edit/downloadable/samples.phtml';
 
     /**
      * Downloadable file