call_hook('post_controller_constructor') causes app to stop

I have inherited a webapp using CodeIgniter I am trying to get it to run locally on my mac for the first time.

When I try to go to http://localhost ,i can see via the some debug logs it is in index.php and CodeIgniter.php. Once in CodeIgniter.php it gets to the line $EXT->call_hook('post_controller_constructor') and then nothing

In the code below i see the first entry in the error_log file, but never the second

error_log("(".__LINE__.") ".__FILE__." -->".__METHOD__." \n");
$EXT->call_hook('post_controller_constructor');
error_log("(".__LINE__.") ".__FILE__." -->".__METHOD__." \n");

There is nothing in php_error.log

The browser says "This site can’t be reached"

I am a total noob to CodeIgniter

This code was ftp'd from a working server.

Would love any suggestions on how to debug this further