By default Cisco Unified Communication Manager (CUCM) negotiates SFTP protocol version 4 (four) upon connecting to SilverSHielD; however, the use of such protocol version may lead to CUCM being unable to handle the response to the GetAttributes command and eventually the backup may fail.
In order to perform a full and clean backup, the best option is to force CUCM to use the SFTPv3 protocol. This can be done by configuring the proper option in SilverSHielD as shown in the image here below.
In the SilverSHielD Management Console, under Expert Settings, disable all protocol versions but SFTP v3. Save your configuration and your CUCM will be forced to use the SFTP v3 protocol when it connects to SilverSHielD.
As of SilverSHielD version 5.4 (and subsequent) you can simply use the handy drop-down menu, that will make the proper configuration for you: