I was receiving the same error today. I re-downloaded the software thinking it might have been corrupted, no change. Even lengthened the delay a touch in Midi-ox to make sure I wasn't over-running any buffers (75 ms). Still no go. I tried several different startup sequences for hardware, still Error 14 and dead except for Update Mode. I am using USB via the Axe II to update, btw, set per the Wiki.
On the 6th attempt (not counting another 5 or 6 where it quit midstream at different percents between 2 and 88% completeness), I finally got it. One difference I noticed was that it actually said the firmware update was complete, instead of just "100% Complete" like it did in the previous attempts, which I thought indicated the full transfer had occurred. Apparently 100% Complete isn't really 100% complete, and without whatever comes after 100%, you're dead in the water.
My final (and working) configuration involved the computer running first, start the Axe II with proper I/O settings already in, power up MFC with #1 down to go into firmware update mode, start midi-ox, Actions>Send SysEx>Select MFC SysEx file. Now mind you, I did this very procedure at least three of the previous unsuccessful attempts, but for some unknown reason it took this time.
I LOVE this controller, and love that FAS offers fixes so readily, but I seriously sweat updating this dude. Last update it's first shot and done. This update it's scare the crap out of me until it feels like the planets are aligned right to take the update. Really weird, but midi has always been finicky in my experience.