Error: Unknown region on packer validate (region newer than Packer)

Error: Unknown region: ap-northeast-2 (packer validate)

TL;DR

Your Packer version predates the AWS region you are targeting. Upgrade Packer (and the amazon plugin) to a release that knows the region, then re-validate.

The error

Build 'amazon-ebs' prepare failure: 1 error(s) occurred:

* Unknown region: ap-northeast-2

Fix it

1. Check your Packer version: packer version. If it predates the region's launch, that is the problem.

• Success check: you have a version number to compare against the region launch date.

1. Upgrade Packer to current, and upgrade the amazon plugin: packer plugins install github.com/hashicorp/amazon.

• Success check: packer version shows the new release.

1. Re-run packer validate.

• Success check: the region is accepted.

1. If you cannot upgrade, verify the region string is spelled correctly (ap-northeast-2, not ap-north-east-2) as a sanity check.

• Success check: the spelling matches the AWS region list.

When to use this

You hit this on packer validate with a region that AWS launched after your Packer release.

When NOT to use this

Do not use this for error validating regions: MissingEndpoint. That is an endpoint configuration problem, not an unknown region.

Compatibility

Older Packer 1.x and the amazon plugin. Current releases know all commercial regions.

Variants

• Unknown region: [any newer region] (af-south-1, eu-south-1, me-south-1, etc. on old builds)
• The same error from packer build at prepare time, not just validate

Root cause

Packer validated regions against a baked-in list. New AWS regions launched after the release were rejected as unknown until the list was updated upstream.

Edge cases

• GovCloud and China regions have always needed explicit endpoint configuration; they fail differently.
• A typo'd region fails the same way on any version. Rule out typos before upgrading.