Resolve "Caused by: java.rmi.server.ExportException: Port already in use" Exception

When running neo4j-admin the below exception is thrown:

Error: Exception thrown by the agent : java.rmi.server.ExportException: Port already in use: 3637; nested exception is:
        java.net.BindException: Address already in use (Bind failed)
jdk.internal.agent.AgentConfigurationError: java.rmi.server.ExportException: Port already in use: 3637; nested exception is:
        java.net.BindException: Address already in use (Bind failed)
        at jdk.management.agent/sun.management.jmxremote.ConnectorBootstrap.startRemoteConnectorServer(ConnectorBootstrap.java:491)
        at jdk.management.agent/jdk.internal.agent.Agent.startAgent(Agent.java:447)
        at jdk.management.agent/jdk.internal.agent.Agent.startAgent(Agent.java:599)
Caused by: java.rmi.server.ExportException: Port already in use: 3637; nested exception is:
        java.net.BindException: Address already in use (Bind failed)
        at java.rmi/sun.rmi.transport.tcp.TCPTransport.listen(TCPTransport.java:335)
        at java.rmi/sun.rmi.transport.tcp.TCPTransport.exportObject(TCPTransport.java:243)
        at java.rmi/sun.rmi.transport.tcp.TCPEndpoint.exportObject(TCPEndpoint.java:412)
        at java.rmi/sun.rmi.transport.LiveRef.exportObject(LiveRef.java:147)
        at java.rmi/sun.rmi.server.UnicastServerRef.exportObject(UnicastServerRef.java:234)
        at java.rmi/sun.rmi.registry.RegistryImpl.setup(RegistryImpl.java:220)
        at java.rmi/sun.rmi.registry.RegistryImpl.<init>(RegistryImpl.java:180)
        at jdk.management.agent/sun.management.jmxremote.SingleEntryRegistry.<init>(SingleEntryRegistry.java:49)
        at jdk.management.agent/sun.management.jmxremote.ConnectorBootstrap.exportMBeanServer(ConnectorBootstrap.java:836)
        at jdk.management.agent/sun.management.jmxremote.ConnectorBootstrap.startRemoteConnectorServer(ConnectorBootstrap.java:479)
        ... 2 more
Caused by: java.net.BindException: Address already in use (Bind failed)
        at java.base/java.net.PlainSocketImpl.socketBind(Native Method)
        at java.base/java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:452)
        at java.base/java.net.ServerSocket.bind(ServerSocket.java:395)
        at java.base/java.net.ServerSocket.<init>(ServerSocket.java:257)
        at java.base/java.net.ServerSocket.<init>(ServerSocket.java:149)
        at java.rmi/sun.rmi.transport.tcp.TCPDirectSocketFactory.createServerSocket(TCPDirectSocketFactory.java:45)
        at java.rmi/sun.rmi.transport.tcp.TCPEndpoint.newServerSocket(TCPEndpoint.java:670)
        at java.rmi/sun.rmi.transport.tcp.TCPTransport.listen(TCPTransport.java:324)
        ... 11 more

Cause

The issue occurs because neo4j-admin launches a separate JVM. When neo4j-admin is executed on the same system as a running Neo4j database instance, the neo4j-admin JVM shares the same neo4j.conf file by default. This includes port and address configurations for JMX which can cause a conflict with the running Neo4j process.

Solution

Here are two examples of how to address this situation by disabling JMX on neo4j-admin:

1. Set JAVA_OPTS
   
   1. Disable JMX or change the port using the JAVA_OPTS environment variable before executing the neo4j-admin command. For example, JAVA_OPTS=’-Dlog4j2.disable.jmx=true’; bin/neo4j-admin ...
2. Create a separate configuration file
   
   1. Make a new directory for a separate configuration file to be used for neo4j-admin. For example, <neo4j home>/conf-admin/.
   2. Copy your current neo4j.conf into the new directory.
   3. In the copied neo4.conf file, set the dbms.jvm.additional=-Dlog4j2.disable.jmx to true. Or, if you wish to log neo4j-admin events with JMX, assign a different (unused) port to dbms.jvm.additional=-Dcom.sun.management.jmxremote.port (With Neo4j 5.x, the configuration setting is renamed to "server.jvm.additional")
   4. After these file edits, assign the directory path to the NEO4J_CONF environment variable when running the neo4j-admin command.