newsupernova/vendor/magento/module-store/etc/adminhtml/di.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Framework\App\FrontControllerInterface">
        <plugin name="default_store_setter" type="Magento\Store\App\FrontController\Plugin\DefaultStore" />
    </type>
    <type name="Magento\Framework\Notification\MessageList">
        <arguments>
            <argument name="messages" xsi:type="array">
                <item name="empty_assigned_group_category" xsi:type="string">Magento\Store\Model\Message\EmptyGroupCategory</item>
            </argument>
        </arguments>
    </type>
</config>