If you’re still running older versions of CodeIgniter, here are a couple of tips to make it work with PHP7.

  1. Make sure to install all PHP tools and libraries that comes with PHP7. I was missing curl.
  2. Change your database driver from mysql to mysqli (application/config/config.php).
  3. Fix the /system/core/Common.php error or as some prefer, upgrade to a newer version.

Considering v2.1.3 is very old (currently 3.1.10) , I’m surprised it works with PHP7 with just a few modifications.