AWS SDK .NET 4.5 "Error unmarshalling response back from AWS. HTTP Status Code: 200 OK" on ListObjectsV2 - aws-sdk-net

Question

I am getting this error trying to list objects in a directory on a bucket. I cannot list from the root of the bucket as it has more than 1000 objects, so I need to drill farther down into the directory list to get what I want. My code works when I display from the root of the bucket, but when I try to add directories at the end of the bucket to list their contents I get this error. "Error unmarshalling response back from AWS. HTTP Status Code: 200 OK", "Root element is missing" on the ListObjectsV2. This is a public S3 bucket so I have included my code below so others can try it. I am using AWS-SDK-NET45.zip and compiling as Visual Basic 2019 for .NET 4.8 within an SSIS Script task. This should work, any ideas on what I am doing wrong? Thanks.
---CODE---
Imports System
Imports System.Data
Imports System.Math
Imports Microsoft.SqlServer.Dts.Runtime
Imports Amazon.S3
Imports Amazon.S3.Model
Imports Amazon.Runtime
Imports Amazon
Imports Amazon.S3.Util
Imports System.Collections.ObjectModel
Imports System.IO
'ScriptMain is the entry point class of the script. Do not change the name, attributes,
'or parent of this class.
<Microsoft.SqlServer.Dts.Tasks.ScriptTask.SSISScriptTaskEntryPointAttribute()>
<System.CLSCompliantAttribute(False)>
Partial Public Class ScriptMain
Inherits Microsoft.SqlServer.Dts.Tasks.ScriptTask.VSTARTScriptObjectModelBase
Public Sub Main()
'
' Add your code here
'
Dim filecol As ObservableCollection(Of String)
Try
'filecol = ListingFiles("/gov-fpac-rma-pubfs-production/pub/References/actuarial_data_master/2023/")
'filecol = ListingFiles("/gov-fpac-rma-pubfs-production/") 'Bucket root
filecol = ListingFiles("/gov-fpac-rma-pubfs-production/pub/")
Dts.TaskResult = ScriptResults.Success
Catch ex As Exception
Console.WriteLine(ex.Message.ToString)
Dts.TaskResult = ScriptResults.Failure
End Try
End Sub
#Region "ScriptResults declaration"
'This enum provides a convenient shorthand within the scope of this class for setting the
'result of the script.
'This code was generated automatically.
Enum ScriptResults
Success = Microsoft.SqlServer.Dts.Runtime.DTSExecResult.Success
Failure = Microsoft.SqlServer.Dts.Runtime.DTSExecResult.Failure
End Enum
#End Region
Private Function ListingFiles(bucketName As String, Optional foldername As String = "/") As ObservableCollection(Of String)
Dim obsv As New ObservableCollection(Of String)
Dim delimiter As String = "/"
Dim AWS_ACCESS_KEY As String = "xxxxxxxxxxxx" 'Add your Access Key here
Dim AWS_SECRET_KEY As String = "xxxxxxxxxxxxxxxxx" ' 'Add your Secret here
Dim s3config As AmazonS3Config = New AmazonS3Config
With s3config
.ForcePathStyle = True
.RegionEndpoint = RegionEndpoint.USEast1
End With
Dim s3Client As AmazonS3Client = New AmazonS3Client(AWS_ACCESS_KEY, AWS_SECRET_KEY, s3config)
If Not foldername.EndsWith(delimiter) Then
foldername = String.Format("{0}{1}", foldername, delimiter)
End If
Try
Try
Dim request As New ListObjectsV2Request()
With request
.BucketName = bucketName
End With
Do
Dim response As New ListObjectsV2Response()
response = s3Client.ListObjectsV2(request)
For i As Integer = 1 To response.S3Objects.Count - 1
Dim entry As S3Object = response.S3Objects(i)
If Not foldername = "/" Then
If entry.Key.ToString.StartsWith(foldername) Then
Dim replacementstring As String = Replace(entry.Key, foldername, "")
If Not replacementstring = "" Then
obsv.Add(replacementstring)
End If
End If
Else
obsv.Add(Replace(entry.Key, foldername, ""))
End If
MessageBox.Show(entry.Key + " " + entry.LastModified.ToString())
'Console.WriteLine("Object - " + entry.Key.ToString())
'Console.WriteLine(" Size - " + entry.Size.ToString())
'Console.WriteLine(" LastModified - " + entry.LastModified.ToString())
'Console.WriteLine(" Storage class - " + entry.StorageClass)
Next
If (response.IsTruncated) Then
request.ContinuationToken = response.NextContinuationToken
Else
request = Nothing
End If
Loop Until IsNothing(request)
Catch ex As AmazonS3Exception
Console.WriteLine(ex.Message.ToString)
Dts.TaskResult = ScriptResults.Failure
End Try
Catch ex As Exception
Console.WriteLine(ex.Message.ToString)
Dts.TaskResult = ScriptResults.Failure
End Try
Return obsv
End Function
End Class

Answer 1

Ok I added the prefix option to the ListObjectsV2Request as follows and it worked. I was able to get list of files from just the directory I wanted. I was side-tracked thinking it worked like the GetObjects function where you have to add the directory to the end of the bucketname and list the file you want in the Entry.Key. Hopefully others will find this of help since I did not find much for examples on this.
Dim request As New ListObjectsV2Request() 'With {.BucketName = bucketName}
With request
.BucketName = "/gov-fpac-rma-pubfs-production"
.Prefix = "pub/References/actuarial_data_master/2023/2023_"
End With