According to Cisco UCS Manager Upgrade and Downgrade Support Tool 4.0(4n) -> 4.2(3) is a direct upgrade (anything older than 4.0(4n) would be an indirect/double upgrade).
Which FI, IOM & server models/generations (e.g. M4/M5/M6)? If you are running FI-6400 with IOM-220x (or possibly IOM-2408), you may be running into CSCwf39400 : IOMs auto upgrade loop with FIs 6400.
Can you try manually upgrading the IOM by updating but not applying the IOM firmware update? This way you can at least get an idea if the IOM will upgrade during auto install without having to reattempt upgrade of the whole infra bundle. then having to roll back when the IOM upgrade fails? Cisco UCS Manager Firmware Management Guide, Release 4.2 | Chapter: Manage Firmware through Cisco UCS Manager | Updating the Firmware on an IOM.
Maybe my reply on thread Cisco UCS-IOM-2208XP auto upgrade keep rebooting and looping the same has something useful. We experienced IOM auto-upgrade issues when upgrading from FI-6248 to FI-6454 because the IOM images were missing from the FI. ... You can check if the IOM image is on the FI:
- UCSM -> Equipment -> Firmware Management -> Images -> (select the IOM, there are a couple) ->
- The name of the image indicates for which IOM model it is, e.g. ucs-2200-6400.4.2.1i.bin.
- Check that field "Present on Fabric" says A, B (for a clustered domain) or A (for a stand-alone FI). If it says "Unknown", it means there is an issue with that image.
Re-uploading the 4.2 infrastructure bundle may solve the "Unknown" issue. If after the re-upload, "Present on Fabric" is still Unknown, Cisco TAC have a command (debug shell access required) to copy/extract the IOM images to the correct location on the FI. (This is basically the fix for CSCwf39400 referenced above).
