This is the human-readable description that accompanies the numeric remote-invocation error code for this Downloader job, explaining in text what the remote call failure meant. Rather than making an admin cross-reference the numeric cucsFirmwareDownloaderFsmRmtInvErrCode against Cisco documentation, this field spells out the reason in plain language directly on the failed download's row. It might read something like 'Connection to peer failed' when the FSM's remote call to coordinate the download with the other fabric interconnect times out.