using a brand new install on a new server
executed
java -jar /opt/jenkins-cli.jar -s http://localhost:8080 help{

Got the following stack trace:
SEVERE: I/O error in channel Chunked connection to http://localhost:8080/cli
java.io.StreamCorruptedException: invalid stream header: 0A0A0A0A
at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:807)
at java.io.ObjectInputStream.<init>(ObjectInputStream.java:302)
at hudson.remoting.ObjectInputStreamEx.<init>(ObjectInputStreamEx.java:48)
at hudson.remoting.AbstractSynchronousByteArrayCommandTransport.read(AbstractSynchronousByteArrayCommandTransport.java:34)
at hudson.remoting.SynchronousCommandTransport$ReaderThread.run(SynchronousCommandTransport.java:48)

hudson.remoting.RequestAbortedException: java.io.StreamCorruptedException: invalid stream header: 0A0A0A0A
at hudson.remoting.Request.abort(Request.java:303)
at hudson.remoting.Channel.terminate(Channel.java:847)
at hudson.remoting.SynchronousCommandTransport$ReaderThread.run(SynchronousCommandTransport.java:69)
at ......remote call to Chunked connection to http://localhost:8080/cli(Native Method)
at hudson.remoting.Channel.attachCallSiteStackTrace(Channel.java:1416)
at hudson.remoting.Request.call(Request.java:172)
at hudson.remoting.Channel.call(Channel.java:780)
at hudson.remoting.RemoteInvocationHandler.invoke(RemoteInvocationHandler.java:249)
at hudson.remoting.$Proxy1.waitForProperty(Unknown Source)
at hudson.remoting.Channel.waitForRemoteProperty(Channel.java:1258)
at hudson.cli.CLI.<init>(CLI.java:141)
at hudson.cli.CLIConnectionFactory.connect(CLIConnectionFactory.java:72)
at hudson.cli.CLI._main(CLI.java:473)
at hudson.cli.CLI.main(CLI.java:384)
Caused by: java.io.StreamCorruptedException: invalid stream header: 0A0A0A0A
at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:807)
at java.io.ObjectInputStream.<init>(ObjectInputStream.java:302)
at hudson.remoting.ObjectInputStreamEx.<init>(ObjectInputStreamEx.java:48)
at hudson.remoting.AbstractSynchronousByteArrayCommandTransport.read(AbstractSynchronousByteArrayCommandTransport.java:34)
at hudson.remoting.SynchronousCommandTransport$ReaderThread.run(SynchronousCommandTransport.java:48)

Found an old issue that suggested making the following change that worked for me. Not sure if this is a bug or a configuration issue, but thought it would be helpful to anyone else who runs into this problem.

I tried the follow solution that worked:
edit /etc/default/jenkins and changed

JAVA_ARGS="-Djava.awt.headless=true"

to

JAVA_ARGS="-Djava.awt.headless=true -Dhudson.diyChunking=false"

and then restarted jenkins (sudo service jenkins restart)
PS. Love jenkins. thank you!