Drupal 7.44 to 7.52 upgrade error

Hi All,

When I am trying to upgrade my site from Drupal 7.44 to 7.52, I am getting this error when I visit the url admin/reports/status
Fatal error: Call to undefined method DatabaseConnection_mysql::utf8mb4IsConfigurable() in modulessystemsystem.install on line 549

When I googled I got lot of answers, I tried out following things in my end

– Added following configurations to my.ini file

default-character-set = utf8mb4

default-character-set = utf8mb4
character-set-connection = utf8mb4
character-set-results = utf8mb4

character-set-client-handshake = FALSE
character-set-server = utf8mb4

collation-server = utf8mb4_general_ci

– Changed Collation and character set of database and tables

ALTER DATABASE example_db CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci;
ALTER TABLE example_advagg_aggregates CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

– Changed settings.php file database details as:-

        'charset' => 'utf8mb4',
	'collation' => 'utf8mb4_general_ci',

Anyone please help me to resolve this issue

Mysql Version I am using is 5.6.21

Drupal version: 

Source: https://www.drupal.org/taxonomy/term/21/feed