ruden

Where is the project repository located? I want to see the code. You have admin access https://github.com/osCommerce

This will be the SaaS platform?

https://www.oscommerce.com/Services&Info

Not necessary, it depends on the task. The peculiarity of hooks is that you can add code without changing the file code.

PHP error log needs to be checked

Yes https://apps.oscommerce.com/p9Yyp

allow_url_fopen should be set to On in php.ini by default

Unfortunately this doesn't work with Ultimate SEO URLs, due to the language session.

Which SEO add-on is installed in the store?

In file sitemap.php this code if (SEARCH_ENGINE_FRIENDLY_URLS == 'true' || (defined('SEO_ENABLED') && SEO_ENABLED == 'true')) { $languages_array = tep_db_query("SELECT code FROM languages"); while ($languages = tep_db_fetch_array($languages_array)) { $file_extension = ($languages['code'] == DEFAULT_LANGUAGE ? '' : '-' . $languages['code']); create_sitemap($file_extension . '.xml'); create_sitemap_catalog($doc, $root, $file_extension . '.xml'); } } else { create_sitemap(); create_sitemap_catalog($doc, $root); } replace with //if (SEARCH_ENGINE_FRIENDLY_URLS == 'true' || (defined('SEO_ENABLED') && SEO_ENABLED == 'true')) { $languages_array = tep_db_query("SELECT code FROM languages"); while ($languages = tep_db_fetch_array($languages_array)) { $file_extension = ($languages['code'] == DEFAULT_LANGUAGE ? '' : '-' . $languages['code']); create_sitemap($file_extension . '.xml'); create_sitemap_catalog($doc, $root, $file_extension . '.xml'); } //} else { // create_sitemap(); // create_sitemap_catalog($doc, $root); //} OR If you know what constant controls the inclusion of your SEO add-on, then just replace SEO_ENABLED with [YOUR_SEO_ADDON_ENABLED]

@mendoh Give a link to your site.

var_dump($_POST['formid'], $sessiontoken); ???

Include class hooks two times remove duplicate in /includes/application_top.php and /admin/includes/application_top.php require(DIR_FS_CATALOG . 'includes/classes/hooks.php');

YES

I find it difficult to answer. View error logs.