How to stop datafeed

Elastic Stack Elasticsearch
3

thank for the quick reply @dkyle.
I used elasticsearch, kibana and x-pack version 5.4.1 .

And example elasticsearch.log.

[2017-07-14T17:34:53,375][WARN ][r.suppressed ] path: /_xpack/ml/datafeeds/datafeed-alert-mem/_stop, params: {datafeed_id=datafeed-alert-mem}
java.lang.NullPointerException: null
at org.elasticsearch.cluster.node.DiscoveryNodes.isAllNodes(DiscoveryNodes.java:232) ~[elasticsearch-5.4.1.jar:5.4.1]
at org.elasticsearch.cluster.node.DiscoveryNodes.resolveNodes(DiscoveryNodes.java:290) ~[elasticsearch-5.4.1.jar:5.4.1]
at org.elasticsearch.action.support.tasks.TransportTasksAction.resolveNodes(TransportTasksAction.java:167) ~[elasticsearch-5.4.1.jar:5.4.1]
at org.elasticsearch.action.support.tasks.TransportTasksAction$AsyncAction.(TransportTasksAction.java:246) ~[elasticsearch-5.4.1.jar:5.4.1]
at org.elasticsearch.action.support.tasks.TransportTasksAction$AsyncAction.(TransportTasksAction.java:231) ~[elasticsearch-5.4.1.jar:5.4.1]
at org.elasticsearch.action.support.tasks.TransportTasksAction.doExecute(TransportTasksAction.java:104) ~[elasticsearch-5.4.1.jar:5.4.1]
at org.elasticsearch.xpack.ml.action.StopDatafeedAction$TransportAction.doExecute(StopDatafeedAction.java:351) ~[?:?]
at org.elasticsearch.xpack.ml.action.StopDatafeedAction$TransportAction.doExecute(StopDatafeedAction.java:265) ~[?:?]
at org.elasticsearch.action.support.TransportAction$RequestFilterChain.proceed(TransportAction.java:170) ~[elasticsearch-5.4.1.jar:5.4.1]
at org.elasticsearch.xpack.security.action.filter.SecurityActionFilter.lambda$apply$1(SecurityActionFilter.java:128) ~[?:?]
at org.elasticsearch.action.ActionListener$1.onResponse(ActionListener.java:59) ~[elasticsearch-5.4.1.jar:5.4.1]
at org.elasticsearch.xpack.security.action.filter.SecurityActionFilter.lambda$authorizeRequest$4(SecurityActionFilter.java:203) ~[?:?]
at org.elasticsearch.xpack.security.authz.AuthorizationUtils$AsyncAuthorizer.maybeRun(AuthorizationUtils.java:127) ~[?:?]
at org.elasticsearch.xpack.security.authz.AuthorizationUtils$AsyncAuthorizer.setRunAsRoles(AuthorizationUtils.java:121) ~[?:?]
at org.elasticsearch.xpack.security.authz.AuthorizationUtils$AsyncAuthorizer.authorize(AuthorizationUtils.java:109) ~[?:?]
at org.elasticsearch.xpack.security.action.filter.SecurityActionFilter.authorizeRequest(SecurityActionFilter.java:205) ~[?:?]
at org.elasticsearch.xpack.security.action.filter.SecurityActionFilter.lambda$applyInternal$3(SecurityActionFilter.java:181) ~[?:?]

thanks.