After the controller reboots, you are not done. Follow these verification steps:
If you have a primary/backup HA pair, you must upgrade the standby first, then fail over. For standalone units, schedule maintenance during off-hours. cisco 2500 series wireless controller firmware update
transfer download datatype code transfer download mode tftp transfer download serverip <TFTP_IP_ADDRESS> transfer download filename <IMAGE_FILE_NAME.aes> transfer download start After the controller reboots, you are not done
(Cisco Controller) > reset system
Run the following commands, replacing placeholders with your IP and filename: 1.2.5: After the controller reboots