Deprecated (8192): Cake\View\ViewBuilder implements the Serializable interface, which is deprecated. Implement __serialize() and __unserialize() instead (or in addition, if support for old PHP versions is necessary) [CORE/src/View/ViewBuilder.php, line 37]
Warning (512): Unable to emit headers. Headers sent in file=/home/u800835374/domains/progressive-hub.com/public_html/vendor/cakephp/cakephp/src/Error/Debugger.php line=971 [CORE/src/Http/ResponseEmitter.php, line 71]
Warning (2): Cannot modify header information - headers already sent by (output started at /home/u800835374/domains/progressive-hub.com/public_html/vendor/cakephp/cakephp/src/Error/Debugger.php:971) [CORE/src/Http/ResponseEmitter.php, line 168]
Warning (2): Cannot modify header information - headers already sent by (output started at /home/u800835374/domains/progressive-hub.com/public_html/vendor/cakephp/cakephp/src/Error/Debugger.php:971) [CORE/src/Http/ResponseEmitter.php, line 197]
Error: Missing Controller

Missing Controller 📋

Cake\Http\Exception\MissingControllerException
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Error Sitemap.xmlController could not be found.

     * @return \Cake\Http\Exception\MissingControllerException
     */
    protected function missingController(ServerRequest $request)
    {
        return new MissingControllerException([
            'class' => $request->getParam('controller'),
            'plugin' => $request->getParam('plugin'),
            'prefix' => $request->getParam('prefix'),
            '_ext' => $request->getParam('_ext'),

In the case you tried to access a plugin controller make sure you added it to your composer file or you use the autoload option for the plugin.

Suggestion Create the class Sitemap.xmlController below in file: src/Controller/Sitemap.xmlController.php

    <?php
    
namespace App\Controller;

    use 
App\Controller\AppController;

    class 
Sitemap.xmlController extends AppController
    
{

    }

If you want to customize this error message, create templates/Error/missing_controller.php