Air-ct2500-k9-2-0-0-0-fus.aes ((new)) Jun 2026

This update takes much longer than a standard image. Expect it to take 30+ minutes with several reboots. Success Indicator: After the final reboot, show sysinfo should display Firmware Version: PIC 16.0

This version (2.0.0.0) is a critical update from the earlier 1.9.0.0 version. Cisco Community Critical Installation Considerations One-Way Upgrade: air-ct2500-k9-2-0-0-0-fus.aes

for the Cisco 2504 Wireless LAN Controller (WLC). This specific update is a critical "bridge" or foundational firmware used to update internal components like the bootloader, field-programmable gate array (FPGA), and BIOS. This update takes much longer than a standard image

Some users have reported specific issues after moving to the 2.0.0.0 FUS, such as legacy Access Points (e.g., Aironet 1142) failing to negotiate full bandwidth (e.g., getting stuck at 20MHz instead of 40MHz) on certain later firmware versions like 8.3.150.0. Cisco Community Licensing and Support End-of-Life: Cisco Community Licensing and Support End-of-Life: The WLC

The WLC will be offline for approximately 45 minutes. Expect multiple reboots during the process.