Updating to 4.2.4, replaced wp-settings.php, web site crashes

Trying to update http://westonslc.com to WordPress from 3.9.2 to 4.2.4. Manual update, not automatic. I downloaded wordpress-4.2.4.zip and expanded it. I copied files from \wordpress-4.2.4\wordpress to \inetpub\wwwroot including all php files, license.txt, and readme.html. If I replace wp-settings.php, my web site crashes. I can replace other files without any problem. I have not yet updated wp-admin and wp-includes. I have read standard and extended update instructions. I do not see any prior posts on this topic. Why does replacing wp-settings.php crash my web site? Can I skip replacing wp-settings.php? My email is westongroupinc@outlook.com. Any advice would be appreciated. Thank you.