CdkStack failed: Error: This stack uses assets

一番最初のdeploy実行時に下記エラーが出ることがあります。

Do you wish to deploy these changes (y/n)? y
CdkStack: deploying...

 ❌  CdkStack failed: Error: This stack uses assets, so the toolkit stack must be deployed to the environment (Run "cdk bootstrap aws://unknown-account/unknown-region")
    at Object.addMetadataAssetsToManifest (/home/kazuma/.anyenv/envs/nodenv/versions/12.9.1/lib/node_modules/aws-cdk/lib/assets.ts:27:11)
    at Object.deployStack (/home/kazuma/.anyenv/envs/nodenv/versions/12.9.1/lib/node_modules/aws-cdk/lib/api/deploy-stack.ts:208:29)
    at processTicksAndRejections (internal/process/task_queues.js:85:5)
    at CdkToolkit.deploy (/home/kazuma/.anyenv/envs/nodenv/versions/12.9.1/lib/node_modules/aws-cdk/lib/cdk-toolkit.ts:184:24)
    at initCommandLine (/home/kazuma/.anyenv/envs/nodenv/versions/12.9.1/lib/node_modules/aws-cdk/bin/cdk.ts:213:9)
This stack uses assets, so the toolkit stack must be deployed to the environment (Run "cdk bootstrap aws://unknown-account/unknown-region")

bootstrapを実行して、S3バケットを作成して、再度deployを実行すればOKです。