We were able to identify the problem , This error was due to a mismatch in the signature key used in the ssh handshake between the switch and SCP/SFTP.  Unchecking the SCP/SFTP  under server options resolved the issue, as we use FTP within CMCNE .
I am using CMCNE12.4.2 build 43:  Every time I run a Technical Support save for a particular switch i get the message SupportSave Operation Failed. Reason : 256 :  Remote Host:Could not connect to remote host.  Has anyone seen this before ?
CMCNE 12.4.2,build 43 , getting error SupportSave Operation Failed. Reason : 256