Index: core/modules/views/views.theme.inc
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- core/modules/views/views.theme.inc	(revision )
+++ core/modules/views/views.theme.inc	(revision )
@@ -447,7 +447,7 @@
           $variables['header'][$field]['wrapper_element'] = $element_label_type;
         }
         // Improves accessibility of complex tables.
-        $variables['header'][$field]['attributes']['id'] = Html::getUniqueId('view-' . $field . '-table-column');
+        $variables['header'][$field]['attributes']->setAttribute('id',Html::getUniqueId('view-' . $field . '-table-column'));
       }
       // Check if header label is not empty.
       if (!empty($variables['header'][$field]['content'])) {