Error when invoking a secured proxy service WSO2 ESB

Issue

When invoking a secure proxy service you might come accross the following exception.

ERROR - AxisEngine The security token could not be authenticated or authorized; nested exception is: 
 javax.security.auth.callback.UnsupportedCallbackException: Check failed : System error
org.apache.axis2.AxisFault: The security token could not be authenticated or authorized; nested exception is: 
 javax.security.auth.callback.UnsupportedCallbackException: Check failed : System error
 at org.apache.rampart.handler.RampartReceiver.setFaultCodeAndThrowAxisFault(RampartReceiver.java:180)
 at org.apache.rampart.handler.RampartReceiver.invoke(RampartReceiver.java:95)
 at org.apache.axis2.engine.Phase.invokeHandler(Phase.java:340)
 at org.apache.axis2.engine.Phase.invoke(Phase.java:313)
 at org.apache.axis2.engine.AxisEngine.invoke(AxisEngine.java:261)
 at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:167)
 at org.wso2.carbon.core.multitenancy.MultitenantMessageReceiver.doSOAP(MultitenantMessageReceiver.java:281)
 at org.wso2.carbon.core.multitenancy.MultitenantMessageReceiver.processRequest(MultitenantMessageReceiver.java:226)
 at org.wso2.carbon.core.multitenancy.MultitenantMessageReceiver.receive(MultitenantMessageReceiver.java:78)
 at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
 at org.apache.synapse.transport.passthru.ServerWorker.processEntityEnclosingRequest(ServerWorker.java:395)
 at org.apache.synapse.transport.passthru.ServerWorker.run(ServerWorker.java:142)
 at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
 at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.ws.security.WSSecurityException: The security token could not be authenticated or authorized; nested exception is: 
 javax.security.auth.callback.UnsupportedCallbackException: Check failed : System error
 at org.apache.ws.security.processor.UsernameTokenProcessor.handleUsernameToken(UsernameTokenProcessor.java:180)
 at org.apache.ws.security.processor.UsernameTokenProcessor.handleToken(UsernameTokenProcessor.java:61)
 at org.apache.ws.security.WSSecurityEngine.processSecurityHeader(WSSecurityEngine.java:332)
 at org.apache.ws.security.WSSecurityEngine.processSecurityHeader(WSSecurityEngine.java:249)
 at org.apache.rampart.RampartEngine.process(RampartEngine.java:214)
 at org.apache.rampart.handler.RampartReceiver.invoke(RampartReceiver.java:92)
 ... 14 more
Caused by: javax.security.auth.callback.UnsupportedCallbackException: Check failed : System error
 at org.wso2.carbon.security.util.ServicePasswordCallbackHandler.handle(ServicePasswordCallbackHandler.java:112)
 at org.apache.rampart.TokenCallbackHandler.handle(TokenCallbackHandler.java:116)
 at org.apache.ws.security.processor.UsernameTokenProcessor.handleUsernameToken(UsernameTokenProcessor.java:168)
 ... 19 more
[2016-02-09 15:15:53,616] ERROR - ServerWorker Error processing POST reguest for : /services/t/test.com/SimpleProxy.SimpleProxyHttpSoap11Endpoint. Error detail: org.apache.axiom.om.impl.dom.ElementImpl cannot be cast to org.apache.axiom.soap.SOAPHeaderBlock. 
java.lang.ClassCastException: org.apache.axiom.om.impl.dom.ElementImpl cannot be cast to org.apache.axiom.soap.SOAPHeaderBlock
 at org.wso2.carbon.security.pox.POXSecurityHandler.isSOAPWithoutSecHeader(POXSecurityHandler.java:362)
 at org.wso2.carbon.security.pox.POXSecurityHandler.invoke(POXSecurityHandler.java:102)
 at org.apache.axis2.engine.Phase.invokeHandler(Phase.java:340)
 at org.apache.axis2.engine.Phase.invoke(Phase.java:313)
 at org.apache.axis2.engine.AxisEngine.invoke(AxisEngine.java:261)
 at org.apache.axis2.engine.AxisEngine.sendFault(AxisEngine.java:515)
 at org.wso2.carbon.core.multitenancy.MultitenantMessageReceiver.doSOAP(MultitenantMessageReceiver.java:325)
 at org.wso2.carbon.core.multitenancy.MultitenantMessageReceiver.processRequest(MultitenantMessageReceiver.java:226)
 at org.wso2.carbon.core.multitenancy.MultitenantMessageReceiver.receive(MultitenantMessageReceiver.java:78)
 at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
 at org.apache.synapse.transport.passthru.ServerWorker.processEntityEnclosingRequest(ServerWorker.java:395)
 at org.apache.synapse.transport.passthru.ServerWorker.run(ServerWorker.java:142)
 at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
 at java.lang.Thread.run(Thread.java:745)

Possible Reason

One possible reason for this error is that the Authentication details (User Credentials) you are parsing are incorrect. The above exception doesn't give any indication about invalid user credentials so the users might get misleaded.

Remedy

If you see the above exception double check the user credentials you are parsing in the WSS header. Also check the allowed roles and the policy. This might be the root cause of the issue.