RDS Aurora PostgreSQL 16.8 disappeared?

Question

We upgraded our RDS Aurora PostgreSQL from 16.6 to 16.8 on 8 April 2025, but recently discovered that 16.8 has vanished from our regions.

Our existing clusters all remain upgraded, but we cannot create any new clusters using 16.8 and our Tofu is experiencing errors with data lookups:

```hcl
data "aws_rds_engine_version" "postgresql" {
  engine  = "aurora-postgresql"
  version = "16.8"
}
```
```
│ Error: no RDS engine versions found: &{DBParameterGroupFamily: DefaultOnly: Engine:0x140028a8570 EngineVersion:0x140028a8640 Filters:[] IncludeAll: ListSupportedCharacterSets:0x1400172a400 ListSupportedTimezones:0x1400172a401 Marker: MaxRecords: noSmithyDocumentSerde:{}}
```

We use `af-south-1` and `eu-west-1`.

We can see 16.8 is available in `us-east-1`.

```bash
$ aws rds describe-db-engine-versions --engine aurora-postgresql --query "DBEngineVersions[].EngineVersion" --output text --region af-south-1 | sort
11.9	11.21	12.9	12.22	13.9	13.11	13.12	13.13	13.14	13.15	13.16	13.18	14.6	14.8	14.9	14.10	14.11	14.12	14.13	14.15	15.3	15.4	15.5	15.6	15.7	15.8	5.10	16.1	16.2	16.3	16.4	16.6
$ aws rds describe-db-engine-versions --engine aurora-postgresql --query "DBEngineVersions[].EngineVersion" --output text --region eu-west-1 | sort
11.9	11.21	12.9	12.22	13.9	13.11	13.12	13.13	13.14	13.15	13.16	13.18	14.6	14.8	14.9	14.10	14.11	14.12	14.13	14.15	15.3	15.4	15.5	15.6	15.7	15.8	5.10	16.1	16.2	16.3	16.4	16.4-limitless	16.6	16.6-limitless
$ aws rds describe-db-engine-versions --engine aurora-postgresql --query "DBEngineVersions[].EngineVersion" --output text --region us-east-1 | sort
11.9	11.21	12.9	12.22	13.9	13.11	13.12	13.13	13.14	13.15	13.16	13.18	13.20	14.6	14.8	14.9	14.10	14.11	14.12	14.13	14.15	14.17	15.3	15.4	15.5	15.6	5.7	15.8	15.10	15.12	16.1	16.2	16.3	16.4	16.4-limitless	16.6	16.6-limitless	16.8
```

[AWS What's New 2025/04 Amazon Aurora now supports PostgreSQL 16.8, 15.12, 14.17 and 13.20](https://aws.amazon.com/about-aws/whats-new/2025/04/amazon-aurora-postgresql-versions) states that:
> These releases are now available in all commercial AWS regions and AWS GovCloud ([..]) Regions, except [.....] regions.

Koushik_D · Accepted Answer

Dear AWS Customer,

Aurora PostgreSQL versions 17.4, 16.8, 15.12, 14.17, and 13.20 completed deployment in all commercial regions on April 7.
An issue was introduced in these versions which can result in database restarts and/or failovers. We have decided to disallow the creation of new clusters and upgrade of existing clusters to these versions while we work on a fix, and they are no longer selectable as creation or upgrade targets. We are going to rollout a new patch release which is expected to complete in all commercial regions by approximately the beginning of May.

Sincerely,
The Amazon RDS Team

re:Post Agent · Answer

Based on the information provided, it appears that Aurora PostgreSQL version 16.8 is indeed no longer available in the af-south-1 and eu-west-1 regions, while it remains available in us-east-1. This situation is unusual and could be due to several factors:

1. Regional rollout: AWS sometimes rolls out new versions to different regions at different times. It's possible that version 16.8 was temporarily available in your regions but has been pulled back for some reason.

2. Version deprecation: In rare cases, AWS might deprecate a specific version if critical issues are discovered. However, this is unlikely for a recent version like 16.8.

3. Regional differences: AWS occasionally has different version availability across regions due to various factors such as regional infrastructure or compliance requirements.

For your existing clusters that were upgraded to 16.8, they should continue to function normally. AWS typically doesn't force downgrades of running instances even if a version is no longer available for new deployments.

Regarding your Terraform (or OpenTofu) code, you'll need to update it to use a version that's available in your target regions. Based on the output you provided, version 16.6 is the latest available version in both af-south-1 and eu-west-1.

To resolve your immediate issue, you could modify your data source to use version 16.6:

```hcl
data "aws_rds_engine_version" "postgresql" {
  engine  = "aurora-postgresql"
  version = "16.6"
}
```

It's recommended to check the AWS documentation or contact AWS support for the most up-to-date information on version availability and any potential issues with version 16.8. They may be able to provide more specific information about why this version is no longer available in your regions and when (or if) it will be re-introduced.

In the meantime, for new cluster creations, you'll need to use version 16.6 or another available version in your target regions. Keep monitoring AWS announcements and documentation for updates on Aurora PostgreSQL version availability in your regions.  
**Sources**  
[Getting a list of available versions in your AWS Region - Amazon Aurora](https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/USER_UpgradeDBInstance.PostgreSQL.UpgradeVersion.html)  
[Amazon Aurora versioning - Amazon Aurora](https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.VersionPolicy.Versioning.html)

RDS Aurora PostgreSQL 16.8 disappeared?

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