I have administrator access to my AWS account and I'm trying to copy a DB snapshot that has has encryption on it. I'm specifying the key ID but it's still giving me the following error:

/opt/homebrew/lib/ruby/gems/3.0.0/gems/aws-sdk-core-3.124.0/lib/seahorse/client/plugins/raise_response_errors.rb:17:in `call': The target KMS key [<my_key_id>] does not exist, is not enabled or you do not have permissions to access it. (Aws::RDS::Errors::KMSKeyNotAccessibleFault)

The only thing that has changed from the time it worked to the time it no longer works is me enabling encryption on the database, so now its snapshots are encrypted. As a result, I've added the kms_key_id parameter to my copy_db_snapshot method.

Here's how I'm doing this with the aws-sdk-rds gem:

  client.copy_db_snapshot({
                            source_db_snapshot_identifier: source_db_arn,
                            target_db_snapshot_identifier: target_db_snapshot_identifier,
                            source_region: source_db_region,
                            kms_key_id: '<my_key_id>'
                          })

I don't quite fully understand this error message. The key definitely exists (I've tried just the key ID and the full ARN), and I definitely have permission. I'm using a key generated by AWS so not sure if this helps.