• Juju DB snap channel: 4.0/stable
  • Juju controller agent: 2.9.0
  • Operating System: Ubuntu 20.04 LTS
  • Deployment: Juju HA


  1. Juju controller does not bind port 37017 / MongoDB Port
  2. Following error log can be found from /var/snap/juju-db/common/logs/mongodb.log
[replication-0] We are too stale to use <IP_ADDRESS>:37017 as a sync source. Blacklisting this sync source because our last fetched timestamp:
[replication-0] could not find member to sycn from


1. Pausing Juju Controller and Juju Database (MongoDB)

Execute on all juju controller

  1. Switch to controller model
juju switch controller
  1. Login to juju controller
juju ssh <machine_id>
  1. Stop all juju controller agent Run following command inside
sudo systemctl stop jujud-machine-<machine_id>.service
  1. Gracefully stop Juju Database (MongoDB)
sudo snap stop juju-db

2. Backup Juju Database

Execute on troubled juju controller

Backup DB

sudo mv /var/snap/juju-db/common/db /var/snap/juju-db/common/db.orig
sudo mkdir /var/snap/juju-db/common/db
sudo chmod 700 /var/snap/juju-db/common/db

3. Start database

Execute on all juju controller

  1. Start all Juju Database (MongoDB)
sudo snap start juju-db
  1. Verify sync process You should see the key statStr has value as SECONDARY
# Get user and password
export user=$(sudo grep tag /var/lib/juju/agents/machine-*/agent.conf | cut -d' ' -f2)
export password=$(sudo grep statepassword /var/lib/juju/agents/machine-*/agent.conf | cut -d' ' -f2)

# Make sure the troubled node already run as SECONDARY
mongo -u "${user}" -p "${password}" --sslAllowInvalidCertificates --ssl --authenticationDatabase admin --eval "printjson(rs.status())"