MigrateMessageController.php

<?php

namespace Drupal\migrate_drupal_ui\Controller;

use Drupal\Core\Link;
use Drupal\Core\Url;
use Drupal\migrate\Controller\MigrateMessageController as BaseMessageController;

/**
 * Provides controller methods for the Message form.
 */
class MigrateMessageController extends BaseMessageController {
    
    /**
     * Displays an overview of migrate messages.
     *
     * @return array
     *   A render array as expected by
     *   \Drupal\Core\Render\RendererInterface::render().
     */
    public function overview() : array {
        $build = parent::overview();
        $description['help'] = [
            '#type' => 'item',
            '#markup' => $this->t('The upgrade process may log messages about steps that require user action or errors. This page allows you to view these messages'),
        ];
        $description['info'] = [
            '#type' => 'item',
            '#markup' => Link::fromTextAndUrl($this->t('Review the detailed upgrade log.'), Url::fromRoute('migrate_drupal_ui.log'))
                ->toString(),
        ];
        return $description + $build;
    }

}