I had some very simple code on a website to handle logins on the root of the site using ion_auth:
if(!$this->ion_auth->logged_in())
{
redirect("/login");
}
That page posts to /auth/login, which is handled by ion_auth. If the login is successful, the user is redirected to the root of the site. Otherwise, they go back to /login to try again. I initially thought I'd forgotten the password, but with a series of var_dump() calls, I found that the login is successful, but the call to $this->ion_auth->logged_in() returns false anyway.
All of this is after the host upgraded to PHP 7 - the code worked before. I've tried upgrading ion_auth, but it didn't help.