After upgrading the Symantec Endpoint Protection Manager (SEPM) to 14.3 RU2 or higher, it fails to update definitions. The installed Symantec Endpoint Protection (SEP) client on that server is version 14.2.
Tamper Protection on the older client may block SEPM from updating properly.
In the <SEPM install directory>\tomcat\logs\lux.log you see the following result code:
Result Code: 0x80004005
SEPM: 14.3 RU2+
Upgrade the SEP client on the SEPM server to 14.3 RU2 or higher to match your SEPM version to resolve this issue.