Error USB Downgrade firmware Kemper Profiling Head

I've had that same error message...

Try this;

Unplug the USB cable

Insert the USB drive

Turn on the Kemper and wait a few seconds and the nanonboot burnFromUSB() ERROR should go away and the OS should load.

Good luck,

What MacOS and computer model are you using?

Quote from Diego1970

High Sierra MacBook pro 2013

you can easily upgrade to the last MAC OS with the open core legacy patcher,
I'm running a MAC Book 13" from 2011 with that.
https://dortania.github.io/OpenCore-Legacy-Patcher/

Quote from Yoda Guitar

you can easily upgrade to the last MAC OS with the open core legacy patcher,
I'm running a MAC Book 13" from 2011 with that.
https://dortania.github.io/OpenCore-Legacy-Patcher/

^ This.

Works like a charm.

My update just failed multiple times, I restarted my Mac, it needed updates. Mac installed all the updates tried again still failed. Shut down Kemper, shut down Rig manager tried again and finally it worked! I think it was the combination of I needed an OS update and then when computer restarted I needed to restart the Kemper. I think I missed that on the final try I paid full attention and it worked. The other times I was noodling on my guitar.