DBParameterGroupNotFound: DBParameterGroup not found: mysql-57-parameter-group

[Adam C]

I'm getting an error on apply:

Terraform will perform the following actions:

  ~ aws_rds_cluster_instance.rdsmain_instance
      db_parameter_group_name: "default.aurora-mysql5.7" => "mysql-57-parameter-group"


Plan: 0 to add, 1 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

aws_rds_cluster_instance.rdsmain_instance: Modifying... (ID: instance-01)
  db_parameter_group_name: "default.aurora-mysql5.7" => "mysql-57-parameter-group"

Error: Error applying plan:

1 error(s) occurred:

* aws_rds_cluster_instance.rdsmain_instance: 1 error(s) occurred:

* aws_rds_cluster_instance.rdsmain_instance: Error modifying DB Instance instance-01: DBParameterGroupNotFound: DBParameterGroup not found: mysql-57-parameter-group
    status code: 404, request id: 3076783a-7ba3-40b7-b8eb-eba5b60ac541

Here's my code -

First, parameter-group.tf

resource "aws_rds_cluster_parameter_group" "default" {
  name = "mysql-57-parameter-group"
  family = "aurora-mysql5.7"

  description = "Managed by Terraform - for MySQL 5.7"
 
  parameter {
    name = "aurora_lab_mode"
    value = "0"
    apply_method = "immediate"
  }

  parameter {
    name = "aurora_lab_mode"
    value = "0"
    apply_method = "immediate"
  }

 
  parameter {
    name = "binlog_cache_size"
    value = "32768"
    apply_method = "immediate"
  }

  parameter {
    name = "binlog_format"
    value = "OFF"
    apply_method = "immediate"
  }

   parameter {
     name = "slow_query_log"
     value = "1"
   }
 
}

And now, server.tf:

resource "aws_rds_cluster" "rdsmain" {
  engine = "${var.db-engine}"
  engine_version = "${var.engine-version}"
  cluster_identifier     = "${var.cluster-identifier}"
  database_name          = "${var.dbname}"
  master_username        = "${var.master-username}"
  master_password        = "${var.password}"
  vpc_security_group_ids = [ "${aws_security_group.rds.id}" ]
  db_subnet_group_name = "aurora-subnet-group"
  #db_subnet_group_name   = "${aws_db_subnet_group.rdsmain_private.name}"
  final_snapshot_identifier = "${var.final-snapshot-identifier}"
  skip_final_snapshot = "${var.skip-final-snapshot}"
  backup_retention_period = "${var.backup-retention-period}"
  enabled_cloudwatch_logs_exports = "${var.cloudwatch-log-exports}"
 
  tags = {
    Name = "${var.instance_name_tag}"
  }
}

resource "aws_rds_cluster_instance" "rdsmain_instance" {
  count                = "${var.instance-count}"
  identifier           = "instance-0${count.index + 1}"
  cluster_identifier   = "${aws_rds_cluster.rdsmain.id}"
  instance_class       = "${var.instance-class}"
  db_subnet_group_name = "aurora-subnet-group"
  #db_subnet_group_name = "${aws_db_subnet_group.rdsmain_private.name}"
  engine               = "${var.db-engine}"
  engine_version       = "${var.engine-version}"
  preferred_maintenance_window   = "${var.maintenance-window}"
  db_parameter_group_name = "${aws_rds_cluster_parameter_group.default.name}"
  #depends_on = ["aws_rds_cluster_parameter_group.default"]
 
  tags = {
    Name = "${var.instance_name_tag}"
  }

}

resource "aws_security_group" "rds" {
  name        = "${var.aws-security-group-name}"
  #vpc_id      = "${aws_vpc.main.id}"
  vpc_id      = "vpc-57bcb535"
  tags = {
    Name = "${var.instance_name_tag}"
  }
}

resource "aws_security_group_rule" "public_to_rds" {
  type              = "ingress"
  from_port         = "${var.port}"
  to_port           = "${var.port}"
  protocol          = "tcp"
  security_group_id = "${aws_security_group.rds.id}"
  cidr_blocks       = ["${var.security-group-cidr-block}"]

}

Why is the parameter group name not being picked up, when I can see it in the AWS console?

TIA

Adam