Problem Upgrading PostGreSQL RDS

If the AWS Management Console is not processing your request correctly, consider using the AWS Command Line Interface (CLI) or one of the AWS SDKs to modify your DB instances:

aws rds modify-db-instance \
    --db-instance-identifier your-instance-identifier \
    --db-instance-class db.t3.medium \
    --engine-version 15.5 \
    --ca-certificate-identifier your-new-certificate-identifier \
    --apply-immediately

Resources:

• RDS: modify-db-instance

I was able to replicate the issue and got the same error message. As a workaround, I performed the upgrade in 2-steps. First, I upgraded the instance class to t3.medium and then performed the upgrade for engine version to 15.5.

I ran a query to check the supported instance classes for PostgreSQL 15.5 and observed that db.t2.medium was not a supported instance class. Hence, I performed the upgrade in two steps.

Hope this helps!

query:

aws rds describe-orderable-db-instance-options --engine postgres --engine-version 15.5 --query "*[].{DBInstanceClass:DBInstanceClass,StorageType:StorageType}|[?StorageType=='gp2']|[].{DBInstanceClass:DBInstanceClass}" --output text

output:

db.m5.12xlarge db.m5.16xlarge db.m5.24xlarge db.m5.2xlarge db.m5.4xlarge db.m5.8xlarge db.m5.large db.m5.xlarge db.m6g.12xlarge db.m6g.16xlarge db.m6g.2xlarge db.m6g.4xlarge db.m6g.8xlarge db.m6g.large db.m6g.xlarge db.m6i.12xlarge db.m6i.16xlarge db.m6i.24xlarge db.m6i.2xlarge db.m6i.32xlarge db.m6i.4xlarge db.m6i.8xlarge db.m6i.large db.m6in.12xlarge db.m6in.16xlarge db.m6in.24xlarge db.m6in.2xlarge db.m6in.32xlarge db.m6in.4xlarge db.m6in.8xlarge db.m6in.large db.m6in.xlarge db.m6i.xlarge db.m7g.12xlarge db.m7g.16xlarge db.m7g.2xlarge db.m7g.4xlarge db.m7g.8xlarge db.m7g.large db.m7g.xlarge db.r5.12xlarge db.r5.16xlarge db.r5.24xlarge db.r5.2xlarge db.r5.4xlarge db.r5.8xlarge db.r5b.12xlarge db.r5b.16xlarge db.r5b.24xlarge db.r5b.2xlarge db.r5b.4xlarge db.r5b.8xlarge db.r5b.large db.r5b.xlarge db.r5.large db.r5.xlarge db.r6g.12xlarge db.r6g.16xlarge db.r6g.2xlarge db.r6g.4xlarge db.r6g.8xlarge db.r6g.large db.r6g.xlarge db.r6i.12xlarge db.r6i.16xlarge db.r6i.24xlarge db.r6i.2xlarge db.r6i.32xlarge db.r6i.4xlarge db.r6i.8xlarge db.r6i.large db.r6in.12xlarge db.r6in.16xlarge db.r6in.24xlarge db.r6in.2xlarge db.r6in.32xlarge db.r6in.4xlarge db.r6in.8xlarge db.r6in.large db.r6in.xlarge db.r6i.xlarge db.r7g.12xlarge db.r7g.16xlarge db.r7g.2xlarge db.r7g.4xlarge db.r7g.8xlarge db.r7g.large db.r7g.xlarge db.t3.2xlarge db.t3.large db.t3.medium db.t3.micro db.t3.small db.t3.xlarge db.t4g.2xlarge db.t4g.large db.t4g.medium db.t4g.micro db.t4g.small db.t4g.xlarge db.x2g.12xlarge db.x2g.16xlarge db.x2g.2xlarge db.x2g.4xlarge db.x2g.8xlarge db.x2g.large db.x2g.xlarge