Reply To: Upgrading to PHP 7.1

Initially, you wrote about this error PHP Fatal error: Call to undefined function get_header() in /www/wp-content/themes/basel/index.php on line 6, right?

But currently, we don’t see this error and any other errors that may be caused by PHP 7.1. There are only some PHP notices but they are thrown by the code in the child theme that was not there initially. You need to fix your custom code or remove it at all to hide these notices.