I had been escaping the Unhandled Exception error every time I log into my ESXi standalone server running v6.5 on N54L and can't be upgraded to v6.7 due to process compatibility. I have finally found the HP Custom image updated to v6.5U3 which appeared to have the fix built into it.
It was quite straightforward update using the l latest 6.5 HP image so as habit I am making notes here for myself and everyone else who may find it useful.
First of all I downloaded HP Custom v6.5U3 image by selecting Offline Bundle.
I then placed it in my datastore e.g. ds001.
Once copied I ran following command line after I was connected to ESXi using ssh.
# esxcli software vib update -d /vmfs/volumes/ds001/VMware-ESXi-6.5.0-Update3-14990892-HPE-preGen9-650.U22.214.171.124.1-Dec2019-depot.zip
This command took few seconds or may be minutes but confirmed that updates have been installed and will take effect after reboot. So I rebooted the host and it worked like magic.
I did not place host in maintenance mode but if you had done that then you can exit maintenance mode after reboot using following command.
# vim-cmd hostsvc/maintenance_mode_exit