Can not upgrade Aurora RDS Postgres version from 12 to 13

Question

I am trying to upgrade Aurora RDS Postgres cluster db.r5.xlarge from version 12.7 to 13.3. I choose Engine version 13.3, default DB cluster parameter group and DB parameter group default.aurora-postgresql13 and choose 'Apply immediately'.

Received error message:

We're sorry, your request to modify DB cluster clone-cluster has failed. Cannot modify engine version because instance clone-cluster is running on an old configuration. Apply any pending maintenance actions on the instance before proceeding with the upgrade

There are no any pending maintenance actions showing in AWS RDS console and I have no idea what configuration they mean.

We are on a free basic support plan no so we cannot get help from AWS. Can anyone please suggest if there's a way to upgrade the whole cluster at once?

Answer 1

I had this issue and contacted AWS support. They said it is a known issue for (some, or all) db.t3 instance types. In my case I was using db.t3.medium.

So the workaround is as follows:

• Change instance type on the cluster to r5.xlarge or db.r6g.large.
• Upgrade to PostgreSQL 13.3
• Change instance type back to db.t3.medium.

Answer 2

Just to add to the other great answers, another possible reason for "old configuration" errors is attempting to upgrade from an old minor version.

I was trying to upgrade from Postgres 12.6 directly to 13.3, which is not supported. Instead, I had to upgrade to 12.7 first and then upgrade to 13.3.

It's written in the docs, but I didn't notice the minor version requirement.