Summary

Bamboo remote agent fails to connect with SSLException: Unsupported or unrecognized SSL message.

Diagnosis

You may see the below error message in the $BAMBOO_AGENT_HOME/atlassian-bamboo-agent.log file

INFO   | jvm 1    | 2023/02/02 13:13:12 | javax.net.ssl.SSLException: Unsupported or unrecognized SSL message
INFO   | jvm 1    | 2023/02/02 13:13:12 |       at sun.security.ssl.SSLSocketInputRecord.handleUnknownRecord(SSLSocketInputRecord.java:457) ~[?:?]

Cause

javax.net.ssl.SSLException: Unsupported or unrecognized SSL message can occur if protocols on the connection address are incorrect.   For example, if you specify a port that is NOT SSL but you choose settings that try to connect via SSL, this can occur.  It is the equivalent of trying to browse HTTPS protocol on a webserver port that is only listening for HTTP protocol.

You can check the configuration on the  Bamboo's Base URL and Broker client URL  in the Administration → Overview → System, select the General configuration page

Solution

1. Verify the configuration of the Bamboo's Base URL and Broker client URL  are with the correct protocol in use. If necessary update the value and restart Bamboo Server.
2. Please check the Bamboo Base URL or the page  Installing a remote agent and  Running a remote agent section to find the correct URL for remote agent installation. Ensure this address is reachable by the server you're running the remote agent from.
3. Verify and if necessary update the $BAMBOO_AGENT_HOME/conf/wrapper.conf file and adjust the wrapper.app.parameter.2=<bamboo-server-URL>/agentServer/ with the correct value and protocol. 
4. Restart the Bamboo Remote Agent

 Please check the below articles for securing Bamboo server and Bamboo remote agent.

• Securing Bamboo with Tomcat using SSL
• Securing your Atlassian applications with SSL using Apache 

• Securing your remote agents