Fatal error: Class 'DrupalDefaultEntityController' not found in comment.module I'm trying to update the Drupal Core of a website, specifically from 7.65 to 7.67.
I've followed the instructions from here. After the process, I've try to access the website without luck, because I'm getting the following error: Fatal error: Class 'DrupalDefaultEntityController' not found in /var/www/html/modules/comment/comment.module on line 1698

I've tried to run the update.php file and clearing the cache from the db several times, without fixing the error. I've also tried to update from 7.65 to 7.66, but the problem persists.

What am I doing wrong?

UPDATE 1

I've tried to follow the instructions written here suggested by the user sivani. Here is the message I am getting: 

DRUPAL_ROOT is /Users/DamianFox/tests/drupal-website/website.&lt;br/&gt;
Bootstrapping to DRUPAL_BOOTSTRAP_SESSION&lt;br/&gt;
&lt;h1&gt;Additional uncaught exception thrown while handling exception.&lt;/h1&gt;&lt;h2&gt;Original&lt;/h2&gt;&lt;p&gt;PDOException: SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: nodename nor servname provided, or not known in lock_may_be_available() (line 167 of /Users/DamianFox/tests/drupal-website/website/includes/lock.inc).&lt;/p&gt;&lt;h2&gt;Additional&lt;/h2&gt;&lt;p&gt;PDOException: SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: nodename nor servname provided, or not known in system_list() (line 165 of /Users/DamianFox/tests/drupal-website/website/includes/module.inc).&lt;/p&gt;&lt;hr /&gt;%
After a bit of research, I found out that the problem might be generated from entity.inc inside the includes folder. 
Therefore, I tried to put back the previous entity.inc (from the 7.65 installation); subsequently, I run the update.php script, and after another refresh, the website is finally accessible. 
I done few more tests to check if there are warnings or errors, but everything seems to work fine, so somehow I got it sorted.