GitHub user maic created a discussion: CloudStack 4.18.0 The client agent
cannot start normally, authentication error
### problem
I added the client through CloudStack UI normally, and it was running normally
before. Suddenly, the client's host status was abnormal, and I checked the logs
and found that it kept reporting SSL certificate abnormalities; The log content
is as follows:
2026-01-22 01:11:56,520 INFO [cloud.agent.Agent] (main:null) (logid:)
Connecting to host:10.58.22.254
2026-01-22 01:11:56,520 INFO [utils.nio.NioClient] (main:null) (logid:)
Connecting to 10.58.22.254:8250
2026-01-22 01:11:56,520 INFO [utils.nio.Link] (main:null) (logid:) Conf file
found: /etc/cloudstack/agent/agent.properties
2026-01-22 01:11:56,593 ERROR [utils.nio.Link] (main:null) (logid:) SSL error
caught during unwrap data: Received fatal alert: certificate_unknown, for local
address=/10.58.22.254:48640, remote address=/10.58.22.254:8250. The client may
have invalid ca-certificates.
2026-01-22 01:11:56,593 ERROR [utils.nio.NioClient] (main:null) (logid:) SSL
Handshake failed while connecting to host: 10.58.22.254 port: 8250
2026-01-22 01:11:56,593 ERROR [utils.nio.NioConnection] (main:null) (logid:)
Unable to initialize the threads.
java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
2026-01-22 01:11:56,593 INFO [utils.nio.NioClient] (main:null) (logid:)
NioClient connection closed
2026-01-22 01:11:56,593 INFO [cloud.agent.Agent] (main:null) (logid:)
Attempted to connect to the server, but received an unexpected exception,
trying again...
com.cloud.utils.exception.NioConnectionException: SSL Handshake failed while
connecting to host: 10.58.22.254 port: 8250
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:101)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
Caused by: java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
... 6 more
2026-01-22 01:12:01,593 INFO [cloud.agent.Agent] (main:null) (logid:)
Connecting to host:10.58.22.254
2026-01-22 01:12:01,593 INFO [utils.nio.NioClient] (main:null) (logid:)
Connecting to 10.58.22.254:8250
2026-01-22 01:12:01,594 INFO [utils.nio.Link] (main:null) (logid:) Conf file
found: /etc/cloudstack/agent/agent.properties
2026-01-22 01:12:01,669 ERROR [utils.nio.Link] (main:null) (logid:) SSL error
caught during unwrap data: Received fatal alert: certificate_unknown, for local
address=/10.58.22.254:48650, remote address=/10.58.22.254:8250. The client may
have invalid ca-certificates.
2026-01-22 01:12:01,669 ERROR [utils.nio.NioClient] (main:null) (logid:) SSL
Handshake failed while connecting to host: 10.58.22.254 port: 8250
2026-01-22 01:12:01,669 ERROR [utils.nio.NioConnection] (main:null) (logid:)
Unable to initialize the threads.
java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
2026-01-22 01:12:01,669 INFO [utils.nio.NioClient] (main:null) (logid:)
NioClient connection closed
2026-01-22 01:12:01,669 INFO [cloud.agent.Agent] (main:null) (logid:)
Attempted to connect to the server, but received an unexpected exception,
trying again...
com.cloud.utils.exception.NioConnectionException: SSL Handshake failed while
connecting to host: 10.58.22.254 port: 8250
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:101)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
Caused by: java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
... 6 more
2026-01-22 01:12:06,669 INFO [cloud.agent.Agent] (main:null) (logid:)
Connecting to host:10.58.22.254
2026-01-22 01:12:06,669 INFO [utils.nio.NioClient] (main:null) (logid:)
Connecting to 10.58.22.254:8250
2026-01-22 01:12:06,670 INFO [utils.nio.Link] (main:null) (logid:) Conf file
found: /etc/cloudstack/agent/agent.properties
2026-01-22 01:12:06,745 ERROR [utils.nio.Link] (main:null) (logid:) SSL error
caught during unwrap data: Received fatal alert: certificate_unknown, for local
address=/10.58.22.254:43360, remote address=/10.58.22.254:8250. The client may
have invalid ca-certificates.
2026-01-22 01:12:06,746 ERROR [utils.nio.NioClient] (main:null) (logid:) SSL
Handshake failed while connecting to host: 10.58.22.254 port: 8250
2026-01-22 01:12:06,746 ERROR [utils.nio.NioConnection] (main:null) (logid:)
Unable to initialize the threads.
java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
2026-01-22 01:12:06,746 INFO [utils.nio.NioClient] (main:null) (logid:)
NioClient connection closed
2026-01-22 01:12:06,746 INFO [cloud.agent.Agent] (main:null) (logid:)
Attempted to connect to the server, but received an unexpected exception,
trying again...
com.cloud.utils.exception.NioConnectionException: SSL Handshake failed while
connecting to host: 10.58.22.254 port: 8250
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:101)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
Caused by: java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
... 6 more
2026-01-22 01:12:11,746 INFO [cloud.agent.Agent] (main:null) (logid:)
Connecting to host:10.58.22.254
2026-01-22 01:12:11,746 INFO [utils.nio.NioClient] (main:null) (logid:)
Connecting to 10.58.22.254:8250
2026-01-22 01:12:11,747 INFO [utils.nio.Link] (main:null) (logid:) Conf file
found: /etc/cloudstack/agent/agent.properties
2026-01-22 01:12:11,822 ERROR [utils.nio.Link] (main:null) (logid:) SSL error
caught during unwrap data: Received fatal alert: certificate_unknown, for local
address=/10.58.22.254:43366, remote address=/10.58.22.254:8250. The client may
have invalid ca-certificates.
2026-01-22 01:12:11,822 ERROR [utils.nio.NioClient] (main:null) (logid:) SSL
Handshake failed while connecting to host: 10.58.22.254 port: 8250
2026-01-22 01:12:11,822 ERROR [utils.nio.NioConnection] (main:null) (logid:)
Unable to initialize the threads.
java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
2026-01-22 01:12:11,822 INFO [utils.nio.NioClient] (main:null) (logid:)
NioClient connection closed
2026-01-22 01:12:11,822 INFO [cloud.agent.Agent] (main:null) (logid:)
Attempted to connect to the server, but received an unexpected exception,
trying again...
com.cloud.utils.exception.NioConnectionException: SSL Handshake failed while
connecting to host: 10.58.22.254 port: 8250
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:101)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
Caused by: java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
... 6 more
2026-01-22 01:12:16,822 INFO [cloud.agent.Agent] (main:null) (logid:)
Connecting to host:10.58.22.254
2026-01-22 01:12:16,822 INFO [utils.nio.NioClient] (main:null) (logid:)
Connecting to 10.58.22.254:8250
2026-01-22 01:12:16,823 INFO [utils.nio.Link] (main:null) (logid:) Conf file
found: /etc/cloudstack/agent/agent.properties
2026-01-22 01:12:16,899 ERROR [utils.nio.Link] (main:null) (logid:) SSL error
caught during unwrap data: Received fatal alert: certificate_unknown, for local
address=/10.58.22.254:56386, remote address=/10.58.22.254:8250. The client may
have invalid ca-certificates.
2026-01-22 01:12:16,900 ERROR [utils.nio.NioClient] (main:null) (logid:) SSL
Handshake failed while connecting to host: 10.58.22.254 port: 8250
2026-01-22 01:12:16,900 ERROR [utils.nio.NioConnection] (main:null) (logid:)
Unable to initialize the threads.
java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
2026-01-22 01:12:16,900 INFO [utils.nio.NioClient] (main:null) (logid:)
NioClient connection closed
2026-01-22 01:12:16,900 INFO [cloud.agent.Agent] (main:null) (logid:)
Attempted to connect to the server, but received an unexpected exception,
trying again...
com.cloud.utils.exception.NioConnectionException: SSL Handshake failed while
connecting to host: 10.58.22.254 port: 8250
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:101)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
Caused by: java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
... 6 more
2026-01-22 01:12:21,900 INFO [cloud.agent.Agent] (main:null) (logid:)
Connecting to host:10.58.22.254
2026-01-22 01:12:21,900 INFO [utils.nio.NioClient] (main:null) (logid:)
Connecting to 10.58.22.254:8250
2026-01-22 01:12:21,901 INFO [utils.nio.Link] (main:null) (logid:) Conf file
found: /etc/cloudstack/agent/agent.properties
2026-01-22 01:12:21,977 ERROR [utils.nio.Link] (main:null) (logid:) SSL error
caught during unwrap data: Received fatal alert: certificate_unknown, for local
address=/10.58.22.254:56392, remote address=/10.58.22.254:8250. The client may
have invalid ca-certificates.
2026-01-22 01:12:21,977 ERROR [utils.nio.NioClient] (main:null) (logid:) SSL
Handshake failed while connecting to host: 10.58.22.254 port: 8250
2026-01-22 01:12:21,977 ERROR [utils.nio.NioConnection] (main:null) (logid:)
Unable to initialize the threads.
java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
2026-01-22 01:12:21,977 INFO [utils.nio.NioClient] (main:null) (logid:)
NioClient connection closed
2026-01-22 01:12:21,977 INFO [cloud.agent.Agent] (main:null) (logid:)
Attempted to connect to the server, but received an unexpected exception,
trying again...
com.cloud.utils.exception.NioConnectionException: SSL Handshake failed while
connecting to host: 10.58.22.254 port: 8250
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:101)
at com.cloud.agent.Agent.start(Agent.java:294)
at com.cloud.agent.AgentShell.launchNewAgent(AgentShell.java:454)
at
com.cloud.agent.AgentShell.launchAgentFromClassInfo(AgentShell.java:431)
at com.cloud.agent.AgentShell.launchAgent(AgentShell.java:415)
at com.cloud.agent.AgentShell.start(AgentShell.java:511)
at com.cloud.agent.AgentShell.main(AgentShell.java:541)
Caused by: java.io.IOException: SSL Handshake failed while connecting to host:
10.58.22.254 port: 8250
at com.cloud.utils.nio.NioClient.init(NioClient.java:67)
at com.cloud.utils.nio.NioConnection.start(NioConnection.java:95)
... 6 more
### versions
CloudStack 4.18.0，KVM
### The steps to reproduce the bug
1.
2.
3.
...
### What to do about it?
_No response_
GitHub link: https://github.com/apache/cloudstack/discussions/12504
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