Upgrade Cisco WLC and access points

I have a small environment with 1 WLC 2504 , that needs to be upgraded from version 8.0.152.0. And then a mix of total 9 access points of 1702 and 2702. They have version: 15.3(3)JA12$

We are experiencing issues with clients unable to connect to the network for example and i want to start off by upgrading the equipment.