IAP-277s are not support in 8.7.x and beyond.
check the release notes for Instant OS 8.7.0 and it mentions it.

------------------------------
If my post was useful accept solution and/or give kudos.
Any opinions expressed here are solely my own and not necessarily that of HPE or Aruba.
------------------------------
Original Message:
Sent: Jan 23, 2024 09:44 AM
From: Arnie
Subject: AIP-277
I have an IAP-277 and need some help please.
I would like to join it to my existing cluster, running on Aruba-Instant 8.10.0.9.
I have upgraded the IAP-277 from the original 6.4.x.x to 8.6.0.23_88342 (Digitally Signed - Production Build), but find that when in the WebGUI, I get an error of "image_check_internal error 001 code 2". which I understand means that there is no upgrade available (?).
Going through all the release note documents, it seems that Instant 8.6.x.x is as far as one can go with the IAP-277, as it is not mentioned in any subsequent release notes. Is this correct ?
I cannot find the a download for Instant in Centaurus flavour beyond 8.6.x.x
Any help appreciated confirm this situation. Thanks