Error "Property 'upload' does not exist on type 'S3Client'" 1. Error "Property 'upload' does not exist on type 'S3Client'" This means you are trying to use the upload method, a feature of the AWS.S3 client in the AWS SDK v2, with the S3Client in the AWS SDK v3. The AWS SDK v3 has a different API and uses command objects instead of direct methods like upload. 2. Understanding the problem between the AWS SDK v2 and the SDK v3: In the AWS SDK v2, you use s3.upload(...) to upload files. In the AWS SDK v3, you use S3Client and PutObjectCommand to upload files. 3. Incorrect API usage: You are trying to use a v2 method with a v3 client. You must use PutObjectCommand to upload a file with the AWS SDK v3.