Critical errors while upgrading onie firmware

Hi,

We might need more information about the switch. What is the switch model? From what firmware version that you want to upgrade to what firmware version? Is the switch working fine? Can you do a show tech for us to have an overview of the switch's information. 

Do you have the full error output? 

Just to confirm, once you have downloaded the ONIE update, have you confirmed the checksum of the file matches the support site checksum info?

Probably you may need to review the ONIE logs, /var/log/onie.log to check if there is any trace of the issue.