S3 general purpose buckets should use cross-Region replication

How to fix it

Add an enabled replication rule pointing at a bucket in a different Region. Versioning has to be on for both buckets, and the rule needs an IAM role S3 can assume. Replication is forward-only, so objects already in the bucket stay unreplicated until you run a Batch Replication job over them. A destination in another account counts as cross-Region here without its Region being confirmed.

In the console

S3 → the bucket → Management → Replication rules

With the AWS CLI

aws s3api put-bucket-replication --bucket <bucket-name> --replication-configuration file://replication.json

With Terraform

resource "aws_s3_bucket_replication_configuration" "this" {
  bucket = var.bucket_name
  role   = var.replication_role_arn

  rule {
    id     = "cross-region"
    status = "Enabled"

    destination {
      bucket = var.destination_bucket_arn
    }
  }
}