3102105 - Error "503 Service Unavailable" occurred while accessing NWA.

Error "503 Service Unavailable" occurred while accessing NWA.

Following errors are outputted in logs:

<std_server0.out>
Start of service:sap.com/engine.security.facade initiate service service:sap.com/tc~sec~vsi~service start due to hard reference.
Service [tc~sec~vsi~service] start ================= ERROR =================
CSN Component [BC-SEC-VIR], DC Name [sap.com/tc~sec~vsi~service]
java.lang.NoClassDefFoundError: com/sap/security/core/server/vsi/api/exception/VSIServiceException
at java.lang.Class.forName0(Native Method)
...
Caused by: java.lang.ClassNotFoundException: com.sap.security.core.server.vsi.api.exception.VSIServiceException
------------------------- Loader Info -------------------------
ClassLoader name: [service:tc~sec~vsi~service]
...

<default trace>
Service [tc~sec~vsi~service] failed to start; nested exception is:
[EXCEPTION]
java.lang.NoClassDefFoundError: com/sap/security/core/server/vsi/api/exception/VSIServiceException
at java.lang.Class.forName0(Native Method)
...
Caused by: java.lang.ClassNotFoundException: com.sap.security.core.server.vsi.api.exception.VSIServiceException
------------------------- Loader Info -------------------------
ClassLoader name: [service:tc~sec~vsi~service]
...

SAP Netweaver 7.1X and above.

nwa, 503, Service Unavailable, Error：Application cannot be started, ClassNotFoundException, tc~sec~vsi~service, netweaver, WebApplicationException log ID , KBA , BC-JAS-COR , Enterprise Runtime, Core J2EE Framework , Problem