This article explains why the " fatal error, failed to open smb device " craft interface error is reported on MX204 and MX10003 Series routers, and indicates whether any action is required to resolve these errors.

On MX204 and MX10003, the following craftd related messages are reported during the commit process:

Aug 13 11:41:34  mx204 mgd[10897]: UI_DBASE_LOGOUT_EVENT: User 'root' exiting configuration mode
Aug 13 11:41:37  mx204 craftd[11470]: craftd detected platform mx10001
Aug 13 11:41:37  mx204 craftd[11470]: LIBJSNMP_SA_IPC_REG_ROWS: ns_subagent_register_mibs: registering 1 rows
Aug 13 11:41:37  mx204 craftd[11470]: fatal error, failed to open smb device: ,JÎÈ <---- Junk char
Aug 13 11:41:37  mx204 jlaunchd: craft-control (PID 11470) exited with status=2
Aug 13 11:41:37  mx204 jlaunchd: Registered PID 11474(craft-control): exec_command
Aug 13 11:41:37  mx204 jlaunchd: craft-control (PID 11474) started
Aug 13 11:41:37  mx204 jlaunchd: Registered PID 11474(craft-control): new process
Aug 13 11:41:37  mx204 jlaunchd: commit-batch (PID 11471) exited with status=0 Normal Exit
Aug 13 11:41:37  mx204 jlaunchd: Registered PID 11475(commit-batch): exec_command
Aug 13 11:41:37  mx204 jlaunchd: commit-batch (PID 11475) started
Aug 13 11:41:37  mx204 jlaunchd: Registered PID 11475(commit-batch): new process

These error messages are reported on MX204 and MX10003 Series routers because these devices do not have craft interfaces. 

These logs are for information purposes only, and can be ignored. To filter out such logs, refer to KB9382 - [Junos Platform] Example - How to prevent certain syslog messages from being written to the log file [juniper.net] . 

When craftd daemon tries to open the device, it fails with a junk character in the fatal error message because the error number is not mapped to a string in the kernel code.
This craftd fatal error message is not generated after fixing PR 1359929 . 

20190226 - Updated with PR 1359929.