Fatal error: Call to undefined function start()

good day
when i try to upgrade my open cart from ver 2.0.1 to the last ver i get this error
Fatal error: Call to undefined function start() in /home/XXXXXXXXXX/public_html/index.php on line 19

Opencart 2302 in not compatible with previous version, and automatic upgrade method is not exist.
You must use clean install of latest version and import your data from previous