Resolve Nodetool/JMX Issue Post k8ssandra-operator Upgrade

Need help fixing nodetool/JMX after k8ssandra-operator upgrade

I upgraded k8ssandra-operator from 1.11.1 → 1.26.0 (Helm chart deployed via Flux).
Operator pods are healthy, Cassandra pods restarted cleanly, and cqlsh works (no data loss).

Problem: nodetool no longer works inside the pod after the upgrade.


kubectl -n cassandra exec -ti cassandra-dc1-rack-1-sts-2 -- \
nodetool -u $CASS_UN -pw $CASS_PS status

Defaulted container "cassandra" out of: cassandra, server-system-logger, server-config-init-base (init), server-config-init (init)
nodetool: Failed to connect to '127.0.0.1:7199' - IOException: '/opt/cassandra/conf/cassandra-jaas.config (No such file or directory)'.


Environment & clues

Cassandra serverVersion: 4.1.3.

Namespace: cassandra. Deployed via HelmRelease in Flux.

Looks like a JMX/JAAS config change with the newer operator/image (file path or auth settings), since data/queries are OK but JMX on 127.0.0.1:7199 fails.

What I need

Quickly restore nodetool access (e.g., status, info, ring) and document the fix (JMX/JAAS settings, env vars, or image/config changes required after the upgrade).

Please don’t bid unless you have real Cassandra/K8ssandra JMX experience.
I’m happy to jump on a call—this should be a quick fix for someone who’s done it before.