OK, so the information in the documentation here is very unclear: https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-serverless-v2.upgrade.html#aurora-serverless-v2.upgrade-from-serverless-v1-procedure
You shouldn't try to migrate the Cluster from Provisioned to Serverless, the option is to convert the DATABASE (Writer instance) in the Provisioned Cluster to Serverless V2!
So, here's the steps that might save someone else a few tries (and hours):
- Create a Snapshot for the existing Aurora Serverless Cluster overview page (takes about 5 minutes (depending on DB size))
- Open snapshots and choose to restore Snapshot to highest available PROVISIONED Aurora Cluster (for me it was Postgres 10.20), no other settings needs to be changed other than "Provisioned" and the version (this will take several minutes, about 15 minutes)
- Refresh now and again using the "refresh" button (as the AWS console "refresh" isn't very reliable) to see when the cluster is ready (database doesn't need to be ready, only the Cluster!)
- Once the Cluster is "available", open the Cluster and click "Modify"
- Choose the DB engine version as 13.6 (this is the only version working for Aurora Serverless v2) then scroll down and click "Continue"
- Select "Apply immediately" and click "Modify Cluster"
- Back on the Cluster overview page, again wait for the Cluster to upgrade (this will take several minutes, about 20 minutes)
- Once the Cluster and database are available, select the DATABASE and choose "Modify"
- Select Serverless v2 and then "Continue"
- Choose to apply Immediately and modify the database
- Wait for it to modify completely and you'll have your new Serverless V2 done!
Another thing to note is that with Aurora V2 we'll apparently have a Cluster and a database attached:
I'd assume this is because with Serverless V2 (which is pretty cool!) you can attach additional read replica databases which will "off-load" your writer instance making it faster...