After upgrade of the client software, Symantec Endpoint Protection (SEP) for Mac no longer updates Network Threat Protection (NTP) definitions.

NTP definitions may show as Not Available or "N/A" as per screenshot below:

SEP for Mac
 

Reboot the system and if that doesn't resolve:

1. Open Terminal

2. Run command: sudo ls "/Library/Application Support/Symantec/Silo/NFM/Settings/1/" and provide administrator password. This will list all the files in the directory.

3. Make note of all files with filenames com.symantec.ips.* where * could be numbers from 0 to X.

4. Delete all aforementioned files by running following command for each file: sudo rm -rf "/Library/Application Support/Symantec/Silo/NFM/Settings/1/com.symantec.ips.*" replacing * with numbers taken from point 3.

5. Restart the system and run Live Update

NOTE: It may render system unstable. If the product behaves unexpectedly please reinstall SEP.