Error type: Could not find a valid session key

Question

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Error type: Could not find a valid session key.

BELOW IS THE CODE RESPONSIBLE FOR THE ERROR "Error type: Could not find a valid session key"

$update_email = civicrm_api3('Email','get', $update_email_params);
            if (isset($update_email['id']) && $update_email['values'][0]['email'] !=$objectRef[$parameters['email']]){
                $update_email_final = civicrm_api3('Email','create', [
                  'sequential'=> 1,
                  'contact_id'=> $custom_44_result['id'],
                  'email'     => $objectRef[$parameters['email']],
                  'is_primary'=> 1,
                  'id' => $update_email['id'],
                ]); 

            }

Above is the update email code snippet which --- when placed gives error Could not find a valid session key --- when removed the error vanishes and process is completed

The complete code is as seen below

define('FirstName2','custom_47');
define('LastName2','custom_48');
define('Email2','custom_50');
define('CID2','custom_49')
add_filter( 'civicrm_post', 'alter_profiles_event', 10, 4  );
function alter_profiles_event($op, $objectName, $objectId, &$objectRef){
  if (is_user_logged_in()){
    if ($objectName == 'Profile'  && ($op == 'edit' ||$op == 'create' ) && isset($objectRef[FirstName1])) {
      $parameters = array(
        'first_name' => FirstName2,
        'last_name' =>LastName2,
        'email' =>Email2,
        'cid' => CID2,
      ); 
      civicrm_alter_family_members($objectRef,$parameters);
    }
  }
}

function civicrm_alter_family_members($objectRef,$parameters) {
   $custom_44_params = [
            'sequential' => 1,
            'contact_type' => "Individual",
            'first_name' => $objectRef[$parameters['first_name']],
            'last_name' => $objectRef[$parameters['last_name']],
          ];

          if (isset($objectRef[$parameters['cid']]) && !empty($objectRef[$parameters['cid']])) {
             $custom_44_params['contact_id'] = $objectRef[$parameters['cid']];
          }

          $custom_44_result = civicrm_api3('Contact','create',$custom_44_params);

          if (!empty($objectRef[$parameters['email']])){

            $update_email_params = [
              'sequential'=> 1,
              'contact_id'=> $custom_44_result['id'],
              'is_primary'=> 1,
            ];
            $update_email = civicrm_api3('Email','get', $update_email_params);
            if (isset($update_email['id']) && $update_email['values'][0]['email'] !=$objectRef[$parameters['email']]){
                $update_email_final = civicrm_api3('Email','create', [
                  'sequential'=> 1,
                  'contact_id'=> $custom_44_result['id'],
                  'email'     => $objectRef[$parameters['email']],
                  'is_primary'=> 1,
                  'id' => $update_email['id'],
                ]); 

            }

       }

}

I see updating civicrm email id gives session key error. I also have

CiviCRM WordPress Profile Sync

plugin enabled. Even when I disabled it, the error was existent. So, ruled out above plugin to be causing the error.

When above CiviCRM email is updated, it updates the Email of the Wordpress User.