Host controller throws error "JBAS014649: Child local of element domain-controller already declared"

Issue

• Why host controller throws following error message at boot time when server started in EAP 6 domain mode?

ERROR [org.jboss.as.host.controller] (Controller Boot Thread) JBAS010932: Caught exception during boot: org.jboss.as.controller.persistence.ConfigurationPersistenceException: JBAS014676: Failed to parse configuration
at org.jboss.as.controller.persistence.XmlConfigurationPersister.load(XmlConfigurationPersister.java:141) [jboss-as-controller-7.1.3.Final-redhat-4.jar:7.1.3.Final-redhat-4]
at org.jboss.as.host.controller.HostControllerConfigurationPersister.load(HostControllerConfigurationPersister.java:158) [jboss-as-host-controller-7.1.3.Final-redhat-4.jar:7.1.3.Final-redhat-4]
at org.jboss.as.host.controller.DomainModelControllerService.boot(DomainModelControllerService.java:382) [jboss-as-host-controller-7.1.3.Final-redhat-4.jar:7.1.3.Final-redhat-4]
at org.jboss.as.controller.AbstractControllerService$1.run(AbstractControllerService.java:156) [jboss-as-controller-7.1.3.Final-redhat-4.jar:7.1.3.Final-redhat-4]
at java.lang.Thread.run(Thread.java:722) [rt.jar:1.7.0_09-icedtea]
Caused by: javax.xml.stream.XMLStreamException: ParseError at [row,col]:[x,x]
Message: JBAS014649: Child local of element domain-controller already declared