I'm uploading files to Amazon S3. I've used the fileNameMethod ="GuidWithExtension" for uploadStreamProvider in web.config but all files are still saved using ClientName(s).

Here's what my web.config entry looks like for uploadStreamProvider:

<uploadStreamProvider type="S3" accessKeyId="myS3AccessId" secretAccessKey="mySecretAccessKeyForS3" bucketName="myS3BucketName" fileNameMethod ="GuidWithExtension" />

What am I doing wrong?

Did you want to do the timestamp or the guid? The problem with the Guid configuration was a documentation issue. It should be "objectNameMethod" (which is only used for the S3 provider) rather than "fileNameMethod" (which is only used for the File provider).

If you want to do the timestamp, you'll need to create your own custom upload stream provider class. It would inherit from S3UploadStreamProvider and override the GetObjectName method. That will allow you to control what key is used to store the file on S3. Something like this:

public class CustomS3UploadStreamProvider : S3UploadStreamProvider
{
        public CustomS3UploadStreamProvider(UploadStreamProviderElement settings)
            : base(settings)
{ }

        public override string GetObjectName(UploadedFile file)
        {
// TODO: return the name you want here
}
}

Then, configurare that provider in the web.config by setting the type attribute to (replacing with whatever names you use):

type="YourNamespace.YourClassName, YourAssemblyName"