Failing to upgrade controller: model is under "importing" mode, upgrade blocked

Thanx to @hpidcock that provided the solution, we have managed to get through this issue.

Steps taken:

  1. Connect to the mongodb

juju-db.mongo 127.0.0.1:37017/juju --authenticationDatabase admin --ssl --sslAllowInvalidCertificates --username machine-0 --password

2. Update datbase as follows:

// update status to available for model 153383c1-7bd8-4f6e-8ec7-be680156f497

db.statuses.updateOne({“_id”:“153383c1-7bd8-4f6e-8ec7-be680156f497”+“:e”},{“$set”: {“status”: “available”}})
// update migration-mode to “” for model 153383c1-7bd8-4f6e-8ec7-be680156f497

db.models.updateOne({“_id”:“153383c1-7bd8-4f6e-8ec7-be680156f497”},{“$set”: {“migration-mode”: “”}})
  1. Upgrade controller juju upgrade-controller

After months being stuck - we are finally on the right side of things again.