This read-only display string is the human-readable error message tied to the extended error code for a failed SNMP operation originating from an IPv4 or IPv6 addressed requester, generally matching what appeared on the management console. An admin reads this directly for a plain-language explanation of an SNMP failure without needing to decode the numeric error code, for requests tracked via the InetAddress-based error table. For example, eqlSNMPInetExtErrMsg might report "Insufficient free space in pool" as the reason an IPv6-based management client's SET request to expand a volume was rejected.