Fix – Notice: get_currentuserinfo is deprecated since version 4.5

Just find in plugin or theme directory with text get_currentuserinfo and replace with wp_get_current_user()

Because of deprecated function get_currentuserinfo and arrived new function _wp_get_current_user() Since: WordPress 4.5.0

function get_currentuserinfo() {
_deprecated_function( __FUNCTION__, '4.5', 'wp_get_current_user()' );
return wp_get_current_user();
}

More info