After update of our Jenkins master installation to its latest LTS version 2.46.3 one of its slaves (Windows 7 machine, 32-bit) cannot connect with the master.
The error we're getting is:
java -jar slave.jar -jnlpUrl https://<jenkins-name>/computer/<node-name>/slave-agent.jnlp -secret <secret-value>
Jun 22, 2017 1:19:05 PM hudson.remoting.jnlp.Main createEngine
INFO: Setting up slave: node-name
Jun 22, 2017 1:19:05 PM hudson.remoting.jnlp.Main$CuiListener <init>
INFO: Jenkins agent is running in headless mode.
Jun 22, 2017 1:19:05 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Locating server among [https://<jenkins-name>/]
Jun 22, 2017 1:19:05 PM org.jenkinsci.remoting.engine.JnlpAgentEndpointResolver resolve
INFO: Remoting server accepts the following protocols: [JNLP3-connect, JNLP-connect, CLI2-connect, Ping, CLI-connect, JNLP4-connect, JNLP2-c
onnect]
Jun 22, 2017 1:19:05 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Agent discovery successful
Agent address: <jenkins-name>
Agent port: <jenkins-port>
Identity: <id:en:ti:ty>
Jun 22, 2017 1:19:05 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Handshaking
Jun 22, 2017 1:19:05 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Connecting to <jenkins-name>:9150
Jun 22, 2017 1:19:05 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Trying protocol: JNLP4-connect
Jun 22, 2017 1:19:05 PM org.jenkinsci.remoting.protocol.impl.AckFilterLayer abort
WARNING: [JNLP4-connect connection to <our-proxy>/10.253.0.11:81] Incorrect acknowledgement sequence, expected 0x0003414333 got 0x4854545044
Jun 22, 2017 1:19:05 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Protocol JNLP4-connect encountered an unexpected exception
java.util.concurrent.ExecutionException: org.jenkinsci.remoting.protocol.impl.ConnectionRefusalException: Connection closed before acknowled
gement sent
at org.jenkinsci.remoting.util.SettableFuture.get(SettableFuture.java:223)
at hudson.remoting.Engine.innerRun(Engine.java:385)
at hudson.remoting.Engine.run(Engine.java:287)
Caused by: org.jenkinsci.remoting.protocol.impl.ConnectionRefusalException: Connection closed before acknowledgement sent
at org.jenkinsci.remoting.protocol.impl.AckFilterLayer.onRecvClosed(AckFilterLayer.java:280)
at org.jenkinsci.remoting.protocol.FilterLayer.abort(FilterLayer.java:164)
at org.jenkinsci.remoting.protocol.impl.AckFilterLayer.abort(AckFilterLayer.java:130)
at org.jenkinsci.remoting.protocol.impl.AckFilterLayer.onRecv(AckFilterLayer.java:258)
at org.jenkinsci.remoting.protocol.ProtocolStack$Ptr.onRecv(ProtocolStack.java:669)
at org.jenkinsci.remoting.protocol.NetworkLayer.onRead(NetworkLayer.java:136)
at org.jenkinsci.remoting.protocol.impl.BIONetworkLayer.access$2200(BIONetworkLayer.java:48)
We spent a lot of time trying to fix the problem. Unfortunately without success.
Do you have an idea what could have caused the problem and how can it be solved?
We recently hit this issue with our AWS-based Jenkins using JNLP for remote integration testing. The remote slave would call back to the Jenkins master, which failed with a similar error. The issue ended up being a dynamically generated AWS ELB of type HTTP (because the Kubernetes ELB provisioner presently doesn't support multi-protocol ELBs) for the Jenkins Master. We had to manually change the JNLP ingress port type of the ELB to TCP, while the web interface ingress 'instance port' was protocol HTTP and 'load balancer' was protocol HTTPS.
You need to check the secret key of the node is intact. If not proper, you have to download the slave.jar and also Run agent from command line with new jar file.
java -jar slave.jar -jnlpUrl http://<ipaddress>:8080/computer/<computername>/slave-agent.jnlp -secret 340d54sdrgtjj334kelkahsdjkf83f1c5120dc2fb74939fcdb7f05e1926049f8d7991
Also to check the java version installed is > 7
This happened to us when a Windows Update or some other silent background update messed with the slave's environment variables. HTTPS_PROXY and HTTP_PROXY had to be re-added, and once that was done we were back in business.
The message:
Incorrect acknowledgement sequence ...
happened for me when I had incorrectly configured a value for the Java property hudson.TcpSlaveAgentListener.port as the same port number as the HTTP port used by Jenkins. The TcpSlaveAgentListener javadoc indicates that is a misconfiguration when it says:
Aside from the HTTP endpoint, Jenkins runs TcpSlaveAgentListener that listens on a TCP socket. Historically this was used for inbound connection from agents (hence the name), but over time it was extended and made generic, so that multiple protocols of different purposes can co-exist on the same socket. (emphasis added)
If the HTTP port was 8080 and the hudson.TcpSlaveAgentListener.port was also 8080, then my JNLP agents failed to connect. As soon as I assigned another value to hudson.TcpSlaveAgentListener.port (like 50000) and restarted Jenkins, my JNLP agents were able to connect.
The stack trace on the failing JNLP agent was:
INFO: Trying protocol: JNLP4-connect
Mar 02, 2019 3:49:29 PM org.jenkinsci.remoting.protocol.impl.AckFilterLayer abort
WARNING: [JNLP4-connect connection to agent.example.com/172.16.16.113:8080] Incorrect acknowledgement sequence, expected 0x000341434b got 0x485454502f
Mar 02, 2019 3:49:29 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Protocol JNLP4-connect encountered an unexpected exception
java.util.concurrent.ExecutionException: org.jenkinsci.remoting.protocol.impl.ConnectionRefusalException: 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: Connection closed before acknowledgement sent
at org.jenkinsci.remoting.protocol.impl.AckFilterLayer.onRecvClosed(AckFilterLayer.java:280)
at org.jenkinsci.remoting.protocol.FilterLayer.abort(FilterLayer.java:164)
at org.jenkinsci.remoting.protocol.impl.AckFilterLayer.abort(AckFilterLayer.java:130)
at org.jenkinsci.remoting.protocol.impl.AckFilterLayer.onRecv(AckFilterLayer.java:258)
at org.jenkinsci.remoting.protocol.ProtocolStack$Ptr.onRecv(ProtocolStack.java:668)
at org.jenkinsci.remoting.protocol.NetworkLayer.onRead(NetworkLayer.java:136)
at org.jenkinsci.remoting.protocol.impl.BIONetworkLayer.access$2200(BIONetworkLayer.java:48)
at org.jenkinsci.remoting.protocol.impl.BIONetworkLayer$Reader.run(BIONetworkLayer.java:283)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at hudson.remoting.Engine$1.lambda$newThread$0(Engine.java:93)
at java.lang.Thread.run(Unknown Source)
Mar 02, 2019 3:49:29 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Connecting to testing-a.markwaite.net:8080
Mar 02, 2019 3:49:29 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Server reports protocol JNLP4-plaintext not supported, skipping
Mar 02, 2019 3:49:29 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Server reports protocol JNLP3-connect not supported, skipping
Mar 02, 2019 3:49:29 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Server reports protocol JNLP2-connect not supported, skipping
Mar 02, 2019 3:49:29 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Server reports protocol JNLP-connect not supported, skipping
Mar 02, 2019 3:49:29 PM hudson.remoting.jnlp.Main$CuiListener error
SEVERE: The server rejected the connection: None of the protocols were accepted
java.lang.Exception: The server rejected the connection: None of the protocols were accepted
at hudson.remoting.Engine.onConnectionRejected(Engine.java:682)
at hudson.remoting.Engine.innerRun(Engine.java:639)
at hudson.remoting.Engine.run(Engine.java:474)
