# Doing logout using backChannelLogout its giving null

**URL:** <https://forum.keycloak.org/t/doing-logout-using-backchannellogout-its-giving-null/15009>\
**Category:** Miscellanaeous\
**Created:** [April 18, 2022, 1:32pm UTC](https://forum.keycloak.org/t/doing-logout-using-backchannellogout-its-giving-null/15009 "2022-04-18T13:32:49Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![haripriya](https://avatars.discourse-cdn.com/v4/letter/h/3d9bf3/32.png) [@haripriya](https://forum.keycloak.org/u/haripriya)\
**Post date:** [April 18, 2022, 1:32pm UTC](https://forum.keycloak.org/t/doing-logout-using-backchannellogout-its-giving-null/15009/1 "2022-04-18T13:32:49Z")

</div>

Hi All,  
When I am clearing the session by using below code  
for (UserSessionModel userSession : userSessions) {

```
        AuthenticationManager.backchannelLogout(context.getSession(), userSession, false);

    }

```

I am getting following error.Please help me out  
[org.keycloak.services] (default task-3) KC-SERVICES0013: Failed authentication: java.lang.NullPointerException  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.authentication.DefaultAuthenticationFlow.processResult(DefaultAuthenticationFlow.java:477)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.authentication.DefaultAuthenticationFlow.processSingleFlowExecutionModel(DefaultAuthenticationFlow.java:440)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.authentication.DefaultAuthenticationFlow.processFlow(DefaultAuthenticationFlow.java:247)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.authentication.DefaultAuthenticationFlow.processSingleFlowExecutionModel(DefaultAuthenticationFlow.java:381)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.authentication.DefaultAuthenticationFlow.processFlow(DefaultAuthenticationFlow.java:247)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.authentication.DefaultAuthenticationFlow.processSingleFlowExecutionModel(DefaultAuthenticationFlow.java:381)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.authentication.DefaultAuthenticationFlow.processFlow(DefaultAuthenticationFlow.java:247)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.authentication.AuthenticationProcessor.authenticateOnly(AuthenticationProcessor.java:976)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.authentication.AuthenticationProcessor.authenticate(AuthenticationProcessor.java:838)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.protocol.AuthorizationEndpointBase.handleBrowserAuthenticationRequest(AuthorizationEndpointBase.java:150)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.protocol.oidc.endpoints.AuthorizationEndpoint.buildAuthorizationCodeAuthorizationResponse(AuthorizationEndpoint.java:464)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.protocol.oidc.endpoints.AuthorizationEndpoint.process(AuthorizationEndpoint.java:160)  
at org.keycloak.keycloak-services@9.0.3//org.keycloak.protocol.oidc.endpoints.AuthorizationEndpoint.buildGet(AuthorizationEndpoint.java:111)  
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)  
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)  
at java.base/java.lang.reflect.Method.invoke(Method.java:566)