Error: Couldn't find specified instance profile (Packer iam_instance_profile)

Error: Couldn't find specified instance profile: ... failed to satisfy constraint (Packer)

TL;DR

iam_instance_profile must be the bare profile name, not a path or ARN. Use test-profile, not /foo/bar/test-profile or the full ARN.

The error

Build 'amazon-ebs' errored after 20 seconds 62 milliseconds: Couldn't find specified instance profile: ValidationError: 1 validation error detected: Value '/foo/bar/test-profile' at 'instanceProfileName' failed to satisfy constraint: Member must satisfy regular expression pattern: [\w+=,.@-]+
	status code: 400

Fix it

1. Take your instance profile ARN and keep only the last segment: arn:aws:iam::[account]:instance-profile/foo/bar/test-profile becomes test-profile.

• Success check: the value contains no /.

1. Set "iam_instance_profile": "test-profile" in the builder.

• Success check: the value matches [\w+=,.@-]+.

1. If your profile genuinely has a path and Packer will not accept it, duplicate the profile without a path as a workaround.

• Success check: the build finds the profile.

1. Re-run packer build.

• Success check: the instance launches with the profile attached.

When to use this

You hit this when the build fails looking up the instance profile, and your value contains /.

When NOT to use this

Do not use this for UnauthorizedOperation on iam:PassRole (that is a permissions gap on your build identity, not the name format).

Compatibility

Packer 1.x, amazon-ebs. The constraint comes from the EC2 API.

Variants

• The same ValidationError when passing a full ARN instead of the name
• Couldn't find specified instance profile when the profile genuinely does not exist (check the name)

Root cause

EC2's instanceProfileName parameter accepts only the name pattern [\w+=,.@-]+, which excludes /. Packer passes the value straight through, so paths fail at the AWS API.

Edge cases

• Profiles with paths in their names are valid in IAM but unusable here. The duplicate-without-path workaround is the escape hatch.
• The error surfaces ~20s in, at instance launch, not at validate time.