I’m using a trusty old Cyclades / Avocent ACS-16 console server in my home-lab.
I got this device a few years ago, and while it’s EOL it still serves its purpose quite well. It even has the fancy Dual-PSU option – No compromises even in the lab environment :).
My device was running firmware 22.214.171.124 and I never got around to upgrade to the most recent version 126.96.36.199 which was published in 2014.
After trying to update via the WebGUI (Using FTP) the binary upgrade file was never accepted (File transfer was not succesful) even after the transfer itself took place.
From my experience, the best way to upgrade is via the Linux shell of the ACS itself.
To do so, proceed as follows:
cd /mnt/flash (Older versions used /proc/flash, coming from 188.8.131.52 it was the first option)
ftp>get FL0536-017.bin zImage (Overwrite existing Firmware Image)
Firmware can be downloaded from the Vertiv site (They acquired Avocent a while ago): https://www.vertiv.com/en-us/support/software-download/it-management/legacy/acs-classic-advanced-console-servers-software-downloads/
Here’s an old upgrade reference, which I used to derive the above steps, but is referencing the old mountpoint: