[domain@localhost:9990 /] /host=master/server=server-one/subsystem=undertow:start
{
    "outcome" => "failed",
    "failure-description" => "WFLYCTL0158: Operation handler failed: java.util.NoSuchElementException: No child 'undertow' exists",
    "rolled-back" => true
}

=>

[Host Controller] 16:15:30,231 ERROR [org.jboss.as.controller.management-operation] (management-handler-thread - 15) WFLYCTL0013: Operation ("restart") failed - address: ([
[Host Controller]     ("host" => "master"),
[Host Controller]     ("server" => "server-one"),
[Host Controller]     ("subsystem" => "undertow")
[Host Controller] ]) - failure description: "WFLYHC0047: Cannot restart server undertow as it is not currently started; it is STOPPED"
[Host Controller] 16:18:43,764 ERROR [org.jboss.as.controller.management-operation] (management-handler-thread - 18) WFLYCTL0013: Operation ("start") failed - address: ([
[Host Controller]     ("host" => "master"),
[Host Controller]     ("server" => "server-one"),
[Host Controller]     ("subsystem" => "undertow")
[Host Controller] ]): java.util.NoSuchElementException: No child 'undertow' exists
[Host Controller]       at org.jboss.dmr.ModelValue.requireChild(ModelValue.java:369)
[Host Controller]       at org.jboss.dmr.ObjectModelValue.requireChild(ObjectModelValue.java:299)
[Host Controller]       at org.jboss.dmr.ModelNode.require(ModelNode.java:870)
[Host Controller]       at org.jboss.as.host.controller.ManagedServerBootCmdFactory.<init>(ManagedServerBootCmdFactory.java:93)
[Host Controller]       at org.jboss.as.host.controller.ServerInventoryImpl.createBootFactory(ServerInventoryImpl.java:629)
[Host Controller]       at org.jboss.as.host.controller.ServerInventoryImpl.startServer(ServerInventoryImpl.java:200)
[Host Controller]       at org.jboss.as.host.controller.operations.ServerStartHandler$1.execute(ServerStartHandler.java:110)
[Host Controller]       at org.jboss.as.controller.AbstractOperationContext.executeStep(AbstractOperationContext.java:728)
[Host Controller]       at org.jboss.as.controller.AbstractOperationContext.doCompleteStep(AbstractOperationContext.java:563)
[Host Controller]       at org.jboss.as.controller.AbstractOperationContext.completeStepInternal(AbstractOperationContext.java:336)
[Host Controller]       at org.jboss.as.controller.AbstractOperationContext.executeOperation(AbstractOperationContext.java:312)
[Host Controller]       at org.jboss.as.controller.OperationContextImpl.executeOperation(OperationContextImpl.java:1160)
[Host Controller]       at org.jboss.as.controller.ModelControllerImpl.internalExecute(ModelControllerImpl.java:356)
[Host Controller]       at org.jboss.as.controller.ModelControllerImpl.execute(ModelControllerImpl.java:215)
[Host Controller]       at org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler.doExecute(ModelControllerClientOperationHandler.java:220)
[Host Controller]       at org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler.access$300(ModelControllerClientOperationHandler.java:147)
[Host Controller]       at org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler$1$1.run(ModelControllerClientOperationHandler.java:169)
[Host Controller]       at org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler$1$1.run(ModelControllerClientOperationHandler.java:165)
[Host Controller]       at java.security.AccessController.doPrivileged(Native Method)
[Host Controller]       at javax.security.auth.Subject.doAs(Subject.java:422)
[Host Controller]       at org.jboss.as.controller.AccessAuditContext.doAs(AccessAuditContext.java:94)
[Host Controller]       at org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler$1.execute(ModelControllerClientOperationHandler.java:165)
[Host Controller]       at org.jboss.as.protocol.mgmt.AbstractMessageHandler$2$1.doExecute(AbstractMessageHandler.java:298)
[Host Controller]       at org.jboss.as.protocol.mgmt.AbstractMessageHandler$AsyncTaskRunner.run(AbstractMessageHandler.java:518)
[Host Controller]       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
[Host Controller]       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
[Host Controller]       at java.lang.Thread.run(Thread.java:745)
[Host Controller]       at org.jboss.threads.JBossThread.run(JBossThread.java:320)

[domain@localhost:9990 /] /host=master/server=server-one/subsystem=undertow:stop
{
    "outcome" => "success",
    "result" => "STOPPED"
}

[domain@localhost:9990 /] /host=master/server=server-one/subsystem=undertow:kill
{"outcome" => "success"}