After following the instruction for "Patching a Fabric from 6.2.0 to 6.2.1"[1], customer tried to roll back the root container by executing "fabric:container-rollback 1.0 root". But the console hanged with following log:

===
io.fabric8.fabric-agent[io.fabric8.agent.DeploymentAgent] : Unable to update agent
java.lang.IllegalStateException: Configuration Admin service has been unregistered
at org.apache.felix.cm.impl.ConfigurationAdminImpl.getConfigurationManager(ConfigurationAdminImpl.java:300)
at org.apache.felix.cm.impl.ConfigurationAdminImpl.listConfigurations(ConfigurationAdminImpl.java:179)
at io.fabric8.agent.service.FeatureConfigInstaller.findExistingConfiguration(FeatureConfigInstaller.java:80)
at io.fabric8.agent.service.FeatureConfigInstaller.installFeatureConfigs(FeatureConfigInstaller.java:91)
at io.fabric8.agent.service.Agent$BaseDeployCallback.installFeatureConfigs(Agent.java:416)
at io.fabric8.agent.service.Deployer.deploy(Deployer.java:767)
at io.fabric8.agent.service.Agent.provision(Agent.java:348)
at io.fabric8.agent.service.Agent.provision(Agent.java:194)
at io.fabric8.agent.DeploymentAgent.doUpdate(DeploymentAgent.java:642)
at io.fabric8.agent.DeploymentAgent$2.run(DeploymentAgent.java:256)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
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)
===

[1]
https://access.redhat.com/documentation/en-US/Red_Hat_JBoss_Fuse/6.2.1/html/Migration_Guide/ESBMigrationPatching-Fabric.html