启动slave agent时报The server rejected the connection: None of the protocols were accepted错误

启动agent时，报如下错误：

信息: Protocol JNLP4-connect encountered an unexpected exception
java.util.concurrent.ExecutionException: org.jenkinsci.remoting.protocol.impl.Co
nnectionRefusalException: Connection closed before acknowledgement sent
        at org.jenkinsci.remoting.util.SettableFuture.get(SettableFuture.java:223)
        at hudson.remoting.Engine.innerRun(Engine.java:614)
        at hudson.remoting.Engine.run(Engine.java:474)
Caused by: org.jenkinsci.remoting.protocol.impl.ConnectionRefusalException: Conn
ection closed before acknowledgement sent
        at org.jenkinsci.remoting.protocol.impl.AckFilterLayer.onRecvClosed(AckF
ilterLayer.java:280)
        at org.jenkinsci.remoting.protocol.FilterLayer.abort(FilterLayer.java:164)
        at org.jenkinsci.remoting.protocol.impl.AckFilterLayer.access$000(AckFilterLayer.java:43)
        at org.jenkinsci.remoting.protocol.impl.AckFilterLayer$1.run(AckFilterLa
yer.java:176)
        at org.jenkinsci.remoting.protocol.IOHub$DelayedRunnable.run(IOHub.java:964)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at hudson.remoting.Engine$1.lambda$newThread$0(Engine.java:93)
        at hudson.remoting.Engine$1$$Lambda$3/167135.run(Unknown Source)
        at java.lang.Thread.run(Thread.java:745)
六月 17, 2019 8:21:50 下午 hudson.remoting.jnlp.Main$CuiListener status
信息: Connecting to 10.8.204.184:32828
六月 17, 2019 8:21:50 下午 hudson.remoting.jnlp.Main$CuiListener status
信息: Server reports protocol JNLP4-plaintext not supported, skipping
六月 17, 2019 8:21:50 下午 hudson.remoting.jnlp.Main$CuiListener status
信息: Server reports protocol JNLP3-connect not supported, skipping
六月 17, 2019 8:21:50 下午 hudson.remoting.jnlp.Main$CuiListener status
信息: Server reports protocol JNLP2-connect not supported, skipping
六月 17, 2019 8:21:50 下午 hudson.remoting.jnlp.Main$CuiListener status
信息: Server reports protocol JNLP-connect not supported, skipping
六月 17, 2019 8:21:50 下午 hudson.remoting.jnlp.Main$CuiListener error
严重: The server rejected the connection: None of the protocols were accepted
java.lang.Exception: The server rejected the connection: None of the protocols w
ere accepted
        at hudson.remoting.Engine.onConnectionRejected(Engine.java:675)
        at hudson.remoting.Engine.innerRun(Engine.java:639)
        at hudson.remoting.Engine.run(Engine.java:474)

解决办法：
jenkins->系统管理->全局安全配置，勾选“Java Web Start Agent Protocol/3 ”

image.png

修改后查看了下运行记录：
JNLP4连接失败后，尝试JNLP3，连接成功，而JNLP4为什么连接失败还不晓得原因