On the SEPM server, navigate to: %ProgramFiles(x86)%\Symantec\Symantec Endpoint Protection Manager\tomcat\logs\ Open licensing.log . Search for “ERROR” or “FAILED.” Common errors:
If you have an active internet connection but your serial number fails to verify, the root cause may be a problem with the Symantec Licensing Server's accessibility. This could be due to firewall rules, proxy configurations, or DNS issues. Check that your SEPM can reach the license validation service. symantec endpoint protection license key verified
What happens when a license expires or is overdeployed (SEP or SES)? On the SEPM server
SEP uses to prevent license key forgery: symantec endpoint protection license key verified