./blueprint.php, around line 82, change from this:

        self::$boot_from = $boot_from;

        /** Set the plugin error flag. */
        $placester_blueprint->has_plugin_error = $this->_has_plugin_error();

        /** Define the famework constants. */
        add_action( 'after_setup_theme', array( &$this, 'constants' ), 1 );

to this:

        self::$boot_from = $boot_from;

        /** Set the plugin error flag. */
        $placester_blueprint = new stdClass();
        $placester_blueprint->has_plugin_error = $this->_has_plugin_error();

        /** Define the famework constants. */
        add_action( 'after_setup_theme', array( &$this, 'constants' ), 1 );

./custom/property-details.php:

There are 3 instances looking like that:

PLS_Format::translate_amenities(&$amenities

Remove the ampersand sign from all of them

./blueprint/functions/formatting.php, around line 267:

Update this:

    function amenities_but($listing_data, $amenities_to_remove) {

to this:

    function amenities_but(&$listing_data, $amenities_to_remove) {