while launching jenkins http://localhost:8080/jenkins , we are getting below error at UI:

org.jvnet.hudson.reactor.ReactorException: java.lang.Error: java.lang.reflect.InvocationTargetException
                at org.jvnet.hudson.reactor.Reactor.execute(Reactor.java:246)
                at jenkins.InitReactorRunner.run(InitReactorRunner.java:43)
                at jenkins.model.Jenkins.executeReactor(Jenkins.java:894)
                at jenkins.model.Jenkins.<init>(Jenkins.java:796)
                at hudson.model.Hudson.<init>(Hudson.java:81)
                at hudson.model.Hudson.<init>(Hudson.java:77)
                at hudson.WebAppMain$2.run(WebAppMain.java:214)
Caused by: java.lang.Error: java.lang.reflect.InvocationTargetException
                at hudson.init.InitializerFinder.invoke(InitializerFinder.java:124)
                at hudson.init.InitializerFinder$TaskImpl.run(InitializerFinder.java:184)
                at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:259)
                at jenkins.model.Jenkins$7.runTask(Jenkins.java:883)
                at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:187)
                at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:94)
                at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
                at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
                at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.reflect.InvocationTargetException
                at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
                at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
                at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
                at java.lang.reflect.Method.invoke(Method.java:597)
                at hudson.init.InitializerFinder.invoke(InitializerFinder.java:120)
                ... 8 more
Caused by: java.lang.NullPointerException
                at org.jenkinsci.main.modules.sshd.SSHD.init(SSHD.java:144)
                ... 13 more


Error while restarting Jenkins via Unixbox:

[root@fiespx123 xuser]# java -jar /usr/local/apache-tomcat-7.0.23/webapps/jenkins/WEB-INF/jenkins-cli.jar -s http://localhost:8080/jenkins restart
Exception in thread "main" java.io.IOException: Server returned HTTP response code: 503 for URL:http://localhost:8080/jenkins/cli
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1459)
        at hudson.cli.FullDuplexHttpStream.<init>(FullDuplexHttpStream.java:77)
        at hudson.cli.CLI.connectViaHttp(CLI.java:156)
        at hudson.cli.CLI.<init>(CLI.java:140)
        at hudson.cli.CLIConnectionFactory.connect(CLIConnectionFactory.java:68)
        at hudson.cli.CLI._main(CLI.java:439)
        at hudson.cli.CLI.main(CLI.java:374)