Working on a ACE30-MOD-K9, I came across the following error when trying to SSH to another host from here:
RSA host key for X.X.X.X has changed and you have requested strict checking.
Host key verification failed
Problem Description: CU hits CSCur53172
But, the solution is pretty easy...
# clear ssh hosts
This happens when the ACE30 has a pre-existing SSH key stored for the remote device and the remote device's key changes.
The command simply clears the buffer of local SSH keys stored for remote hosts.
Hope it helps another people.