Comment 9 for bug 1979092

Hi Alex,
I just run into the same problem when doing upgrade from 3.8/stable to 3.9/stable. This is single node deployment

# juju status
juju status rabbitmq-serve
Model Controller Cloud/Region Version SLA Timestamp
octavia wilkmarcin-stsstack stsstack/stsstack 2.9.46 unsupported 10:40:42Z

App Version Status Scale Charm Channel Rev Exposed Message
rabbitmq-server 3.8.2 waiting 1 rabbitmq-server 3.9/stable 183 no Not reached target cluster-partition-handling mode

Unit Workload Agent Machine Public address Ports Message
rabbitmq-server/0* waiting idle 24 10.5.2.68 5672/tcp,15672/tcp Not reached target cluster-partition-handling mode

Machine State Address Inst id Series AZ Message
24 started 10.5.2.68 5a1b7e48-cb3a-4399-96fa-fa4c6f862897 focal nova ACTIVE

# config option
juju config rabbitmq-server cluster-partition-handling
ignore

# leader-get
juju run -u rabbitmq-server/0 -- leader-get
__leader_get_migrated_settings__: '["octavia.passwd", "glance.passwd", "neutron.passwd",
  "cinder.passwd", "ceilometer.passwd", "nova.passwd"]'
ceilometer.passwd: zZpPS8j9Xt8ScT5nCHMJkkx8prVxBZJwrmpBNTmjV3x96PYcMpTSbgydG9jncYpZ
cinder.passwd: b3RWy47px6FZXJmtzRRgGy8w3TKyXtRVFj5mNdCh3gmsxR9CXCss7T8cnLp3HghN
coordinator: '{"rabbitmq-server/0": {}}'
glance.passwd: f87n8wpgyhsNgp2ysbmshGT4zthBpYYZtw234zxL2B2tWKnpX5MTMMPgk8dsLPHz
neutron.passwd: LY87mZcckFjMr4jbKmJwBM3GW477p4rVdYdCWSMtwHbkmXhcrVzpx8gMfr3tsX4B
nova.passwd: Hm3VFHXjk8twFskwC3LTzBFbLzKMc7VSf8PRwBwY9yrdpr5MHgwm4PmRyBCtr2BH
octavia.passwd: 2hBqfkhbjmZMj3zV3wm6zcHFxT4YrjtjjcjFxT3ZrKXGw7sVVM5BtbHxx4T8x6ZC

# from the unit:
ubuntu@juju-5ef7f4-octavia-24:~$ sudo rabbitmqctl eval 'application:get_all_env(rabbit).' | grep cluster_partition_handling
 {cluster_partition_handling,ignore},
ubuntu@juju-5ef7f4-octavia-24:~$ grep cluster_partition_handling /etc/rabbitmq/rabbitmq.conf
cluster_partition_handling = ignore

Thanks
Marcin