Symantec Endpoint Protection (SEP) clients in certain client groups fail to register with their Symantec Endpoint Protection Manager (SEPM). Clients that are already registered with the SEPM continue to function normally.

If Sylink debugging is enabled on affected clients, the following line is written to the sylink.log during a failed registration:

07/02 02:11:14.132 [31676] <SentRegistrationRequest:>SMS return=500
07/02 02:11:14.132 [31676] <ParseHTTPStatusCode:>500=>500 INTERNAL SERVER ERROR
07/02 02:11:14.132 [31676] HTTP returns status code=500

the following error is written to the manger's scm-server-0/1.log:

2013-07-02 02:11:14.120 THREAD 144743 SEVERE: The Default Group blocks new clients. The client cannot register with the Default Group.
com.sygate.scm.server.util.ServerException: The Default Group blocks new clients. The client cannot register with the Default Group.

This problem happens when the client group the SEP client is attempting to register with is configured to block new client registrations. 

If you do not intend to block new clients from registering with the affected client group, you must disable blocking new client registrations:

1. Log in to the Symantec Endpoint Protection Manager (SEPM).
2. Click Clients and select the affected client group.
3. Right click the affected client group and click Properties.
4. Un check Block New Clients and click OK.
5. Confirm the affected client(s) are able to register with the SEPM in the affected client group.