Cisco Cisco 2106 Wireless LAN Controller

You can upgrade or downgrade the controller software only between two releases. To upgrade or 
downgrade beyond two releases, you must first install an intermediate release. For example, if your 
controller is running a 4.1 or 4.2 software release, you can upgrade your controller directly to 
software release 5.0.148.0. If your controller is running a 3.2 or 4.0 release, you must upgrade your 
controller to an intermediate release prior to upgrading to 5.0.148.0. 

 shows the upgrade path 

that you must follow before downloading software release 5.0.148.0.

When you upgrade the controller to an intermediate software release, wait until all of the 
access points joined to the controller are upgraded to the intermediate release before you 
install the 5.0.148.0 software. In large networks, it can take some time to download the 
software on each access point.

Cisco recommends that you also install the Cisco Unified Wireless Network Controller Boot 
Software 5.0.148.0 ER.aes file on the controller. This file resolves defect CSCsd52483 and is 
necessary to ensure proper operation of the controller. The ER.aes file can be installed on all 
controller platforms. If you do not install this ER.aes file, your controller does not obtain the fix for 
this defect, and “Error” appears in the Bootloader Version field in the output of the show sysinfo 
command.

Unlike previous ER images, a new bootloader file is not loaded when you install the 
5.0.148.0 ER.aes file. This is true for all controllers. The 4.2.112.0 ER.aes file is the last ER 
file to contain a bootloader. If you want the latest bootloader, install the 4.2.112.0 ER.aes 
file. If you want to obtain the fix for CSCsd52483, also install the 5.0.148.0 ER.aes file.

The ER.aes files are independent from the controller software files. You can run any 
controller software file with any ER.aes file. However, installing the latest boot software file 
(5.0.148.0 ER.aes) ensures that the boot software modifications in all of the previous and 
current boot software ER.aes files are installed.

If you require a downgrade from one release to another, you may lose the configuration from your 
current release. The workaround is to reload the previous controller configuration files saved on the 
backup server or to reconfigure the controller.

3.2.78.0 or later 3.2 release

Upgrade to 4.0.206.0 (or a later 4.0 release) before upgrading to 
5.0.148.0.

4.0.155.5

Upgrade to 4.0.206.0 (or a later 4.0 release) before upgrading to 
5.0.148.0.

4.0.179.11

4.0.206.0 or later 4.0 release

You can upgrade directly to 5.0.148.0.

4.1.171.0 or later 4.1 release

You can upgrade directly to 5.0.148.0.

4.2.61.0 or later 4.2 release

You can upgrade directly to 5.0.148.0.