first. Version 1.9.0.0 or higher is required before moving to AireOS 8.4 or higher. Backup Configuration upload your configuration file to a TFTP/SFTP server before starting as a safety measure. 2. Step-by-Step Update Process (GUI) Release Notes - Cisco 2500 Series Wireless Controllers

As you upgrade through the 8.x release train, several powerful features were added to this legacy platform:

: Large-scale deployments often use Cisco Prime Infrastructure or the Wireless Control System (WCS) for automated rollouts. The Upgrade Process and Impact

To avoid all 50+ APs rebooting simultaneously after the controller reboots, use AP Pre-image download: