5520 8.2.170.0 AP Pre-download failed?

[erickalvarado]

We recently had to upgrade our 5520 to 8.2.170.0 from 8.1.131.0
To speed up the process, I had pre-downloaded the new image to all APs (a mix of 3502i & 3702i). So we rebooted the controller, and after it completed the boot process, all the 3702 APs joined without issue. The 3502s did not join and instead, it looked like they were downloading the new code.

After a while, all the 3502s finished picking up the new code and joined. I am at a miss why they failed since I had pre-downloaded the code to all APs. 

 Has anyone ran into this before?

[Scott Fella]

Not really that it failed, but for example when you decide to upgrade to 8.5, pre download will not work with the 3702’s. The AP has two part downloads and once it gets the first, it will reboot and get the second and reboot.

[erickalvarado]

Is this documented somewhere? I think I saw a similar note on CSCvg41698

[Scott Fella]

Here is what I found:

The image format of Cisco Aironet 1700, 2700, 3700, and IW3702 APs has been changed from ap3g2 to c3700. Therefore, if you are upgrading to Release 8.5 or a later release from Release 8.3 or an earlier release, these APs will download the image twice and reboot twice.
https://www.cisco.com/c/en/us/td/docs/wireless/controller/release/notes/crn85mr2.html#upgrade-software_85mr2

[erickalvarado]

Thank you Scott. Interesting to know. I'll keep that in mind for future upgrades.