When looking for the latest iLO2 firmware for HP Proliant DL380 Gen 5 on the HPE website I found version 2.27 dated in 2015. To resolve browser issues with modern browsers I wanted to find a later firmware.
On this site you will find an exellent collection of all the latest iLO firmwares: https://pingtool.org/latest-hp-ilo-firmwares/
The latest listed iLO2 firmware is 2.33 dated march 2018 (when writing this post). The download links leads to HP sites so it should be legitimate. However, when unpacking the archive and investigating the Readme-file, only Gen 6 servers where listed.
It turns out the firmware works fine on my DL380 Gen 5 iLO2. Upgrade had to be done through Microsoft Internet Explorer 11, otherwise when trying to upgrade through other browsers I got the error message “here. The simple solution was to upgrade through MSIE 11..” described
Disclaimer: I can’t garantuee this will work for you or not get you in trouble with your system using the above procedure. It is just a description of what worked for me.