https://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/68835-wlc-upgrade.html
Upgrade Process for AireOS Wireless LAN Controllers - Cisco
This document describes and explains the procedure and requirements to upgrade software on a Wireless LAN Controller (WLC).
wireless lan controllersupgrade processaireoscisco
https://www.cisco.com/c/en/us/support/docs/wireless/4400-series-wireless-lan-controllers/69719-wlc-lwap-config.html
Configure AireOS Wireless LAN Controller and Lightweight Access Point - Cisco
This document describes the configuration steps to register the Lightweight Access Point to the WLC and basic operation of the LWAPP wireless network.
wireless lan controlleraccess pointconfigureaireoslightweight
https://www.cisco.com/c/en/us/support/docs/field-notices/724/fn72415.html
Field Notice: FN72415 - QuoVadis Root CA 2 Decommission Might Affect AireOS Smart Licensing and...
For affected versions of the AireOS software, some Secure Sockets Layer (SSL) certificates issued from the QuoVadis root certificate authority (CA) trust chain...