Fix broken 4.1 update

fix.php

<?php
define('JOOMLA_MINIMUM_PHP', '7.2.5');

if (version_compare(PHP_VERSION, JOOMLA_MINIMUM_PHP, '<')) {
	die(str_replace(
			'{{phpversion}}',
			JOOMLA_MINIMUM_PHP,
			file_get_contents(dirname(__FILE__) . '/templates/system/incompatible.html')
		));
}

// Constant that is checked in included files to prevent direct access.
define('_JEXEC', 1);
define('JPATH_BASE', __DIR__);

if (file_exists(__DIR__ . '/includes/defines.php')) {
	require_once __DIR__ . '/includes/defines.php';
}
if (!defined('_JDEFINES')) {
	require_once JPATH_BASE . '/includes/defines.php';
}

// Check for presence of vendor dependencies not included in the git repository
if (!file_exists(JPATH_LIBRARIES . '/vendor/autoload.php') || !is_dir(JPATH_ROOT . '/media/vendor')) {
	echo file_get_contents(JPATH_ROOT . '/templates/system/build_incomplete.html');
	exit;
}

// Add the JLoader, etc...
require_once JPATH_BASE . '/includes/framework.php';

// Boot the DI container
$container = \Joomla\CMS\Factory::getContainer();
$db        = \Joomla\CMS\Factory::getContainer()->get('DatabaseDriver');
$msg       = [];

foreach(['atum', 'cassiopeia'] as $template) {
	$clientId = $template === 'atum' ? 1 : 0;
	$query = $db->getQuery(true)
		->update($db->quoteName('#__template_styles'))
		->set($db->quoteName('inheritable') . ' = 1')
		->where($db->quoteName('template') . ' = ' . $db->quote($template))
		->where($db->quoteName('client_id') . ' = ' . $clientId);

	try {
		$db->setQuery($query)->execute();
	} catch (Exception $e) {
		$msg[] = \Joomla\CMS\Language\Text::sprintf('JLIB_DATABASE_ERROR_FUNCTION_FAILED', $e->getCode(), $e->getMessage()) . '<br>';
	}
}

echo implode('<br>', count($msg) ? $msg : ['Successfully updated the template styles']);
die;

instructions.md

• Upload the file fix.php in your server at the root folder (where the .htaccess and the index.php are)
• Temporarily rename .htaccess to .htaccess.bak (needed only for sites with AdminTools)
• Visit your site's /fix.php (eg https://mydonain.tld/fix.php)
• Delete the fix.php file
• Restore .htaccess.bak to .htaccess (needed only for sites with AdminTools)

This is not fixing my problem - both templates are still gone!

This is not fixing my problem - both templates are still gone!

Then you have another problem, probably your update was unsuccessful and you're missing files.

Hmm.. but the update went through without errors.. How do I reinstall core files in joomla 4.1 ? Is that not possible anymore like in 3.x ?

And the problem only arose after doing the database repair !? It worked before the repair.

Top, thx! 👍🏼