There are no 'Private' subnet groups in this VPC. Available types: Public

I’m trying to create a new RDS instance in an isolated subnet of a VPC that I’m creating.

Reproduction Steps

const rdsVpc = new ec2.Vpc(this, 'MyVpc', {
	natGateways: 0,
	subnetConfiguration: [
		{
			cidrMask: 28,
			name: 'rds',
			subnetType: ec2.SubnetType.ISOLATED
		}
	]
});

const dbInstance = new rds.DatabaseInstance(this, 'MyRdsInstance', {
	engine: rds.DatabaseInstanceEngine.POSTGRES,
	instanceClass: new ec2.InstanceType('t3.micro'),
	masterUsername: 'admin',
	databaseName: 'mydb',
	masterUserPassword: this.dbSecretManager.secretValue,
	vpcPlacement: {
		subnetType: SubnetType.ISOLATED
	},
	vpc: rdsVpc
});

Error Log

There are no ‘Private’ subnet groups in this VPC. Available types: Public

Environment

• CLI Version : 1.31.0
• **Framework Version: **
• OS : MacOS Catalina
• Language : Typescript

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This is 🐛 Bug Report

[evan-beatdapp]

If anyone stumbles on this and nothing above fixed it - try deleting cdk.context.json.

[shiromoto-jun]

I was looking for a solution for “There are no’Public’ subnet groups in this VPC. Available types:” and got here.

If you create the VPC and subnet in a separate stack, vpc.publicSubnets and vpc.privateSubnets will return an empty array. Do you need a special way to register a subnet in your VPC?