title: PHP7 session warning - session_write_close
body: <p>With an upgrade to from PHP5.6 to PHP7, I am confronted with this error:</p>
  
  <pre><code>sapi_apache2.c(326): PHP Warning:  session_write_close(): Failed to write session data (user). Please verify that the current setting of session.save_path is correct (/var/lib/php/7.0/session)
  </code></pre>
  
  <p>This is odd, because we use a custom session handler, which writes to a database.</p>
  
  <p>What changed in PHP7?</p>