# [LIBDFWD_CB_FUNC_NULL](https://apps.juniper.net/syslog-explorer/?msg=LIBDFWD_CB_FUNC_NULL)

## SYSLOG Details
- **Message**: None of the <variable>argument</variable> callback functions should be NULL.
- **Help**: callback function is NULL
- **Description**: libdfwd found that one of the callback functions is null. It is required that none of the callback functions should be null.
- **Type**: Internal: Internal log message
- **Severity**: error
- **Cause**: -
- **Action**: Contact your technical support representative.
- **Attributes**: argument
- **Facility**: LOG_DAEMON

## Found this message in the following releases:
- [Junos OS 24.2R1](https://apps.juniper.net/syslog-explorer/?msg=LIBDFWD_CB_FUNC_NULL&sw=Junos%20OS&rel=24.2R1)
- [Junos OS 23.4R1](https://apps.juniper.net/syslog-explorer/?msg=LIBDFWD_CB_FUNC_NULL&sw=Junos%20OS&rel=23.4R1)