merge('key_value') ->condition('collection', 'system.schema') ->condition('name', 'update_test_postupdate') ->fields([ 'collection' => 'system.schema', 'name' => 'update_test_postupdate', 'value' => 'i:8000;', ]) ->execute(); // Update core.extension. $extensions = $connection->select('config') ->fields('config', ['data']) ->condition('collection', '') ->condition('name', 'core.extension') ->execute() ->fetchField(); $extensions = unserialize($extensions); $extensions['module']['update_test_postupdate'] = 8000; $connection->update('config') ->fields([ 'data' => serialize($extensions), ]) ->condition('collection', '') ->condition('name', 'core.extension') ->execute();