In Help > Troubleshooting > Connection Status, you see the error "HTTP error: [code]," where [code] is a number.
This is a general error message indicating that communication with the server failed.
If Error 503 appears in Connection Status, this can indicate that the SemSrv service is not running or is in an error state on the server. To solve the problem, make sure that the SemSrv service is running on the server, or stop and restart the service manually.
Run the Symantec Help tool to diagnose the problem.