Why does running nodetool return the following exception?

nodetool: Failed to connect to '' - \
  URISyntaxException: 'Malformed IPv6 address at index 7: rmi://[]:7199'.

This question is commonly reported by Cassandra users after upgrading Java on servers.

1 Answer 1


Root cause

The URL parser for JNDI providers which includes RMI (used by JMX) has been improved in Oracle Java 8u331 and brackets are only allowed around IPv6 addresses (JDK-8278972).

Attempts to run nodetool with newer Java versions breaks because the host in the RMI URL is enclosed in square brackets (from NodeProbe.java class):

    private static final String fmtUrl = "service:jmx:rmi:///jndi/rmi://[%s]:%d/jmxrmi";


OPTION 1 - Add the "legacy" parsing flag when running nodetool, for example:

$ nodetool -Dcom.sun.jndi.rmiURLParsing=legacy status

OPTION 2 - Specify the hostname with an IPv6 subnet prefix, for example:

$ nodetool -h ::FFFF: status


This issue has been addressed in Apache Cassandra 3.0.27, 3.11.13, 4.0.4 and 4.1 releases (CASSANDRA-17581).

Upgrade to the latest patch release to fix the issue in your cluster. Cheers!

Republished from DataStax Community.

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