I've been working on a new site for the last several months. It runs great locally, but when I started thinking of putting it on a live server, I ran into a series of problems. I was hoping that I could simply upgrade my web server from PHP 5.6 to PHP 7, then deploy my Drupal 8 site in place. Sounds simple, right? unfortunately, PHP 7 introduced compatibility-breaking changes which caused problems for my old, Drupal 7-powered site.