How to deactivate all the notices, warnings in debug mode?

These messages are just notices with additional information for developers. Sometimes, they occur after updates for plugins when debug mode is in an active state. After deactivation the will not appear anymore.

To turn off these diagnostic messages, please open in code editor file wp-config.php in the root of your WordPress installation and go approximately to line # 80. Change code:

define('WP_DEBUG', true);

to the following one:

define('WP_DEBUG', false);
define('WP_DEBUG_LOG', false);
define('WP_DEBUG_DISPLAY', false);
define('SCRIPT_DEBUG', false);
define('SAVEQUERIES', false);
ini_set('error_reporting', E_ALL );

Then save changes and check results at the front-end. All messages will disappear.