VB.NET Count number of files to copy with WebClient - arrays

Question

I'm trying to write a code that copy files from a folder to another folder with a progress bar and with a Label that count files, like Copying 0 files of 10 files. but my code is not working and throws and error.
Collection was modified; enumeration operation may not execute.
this is my code:
Imports System.IO
Imports System.Net
Public Class Form1
Dim filesToCopy As New ArrayList()
Protected Overrides Sub OnLoad(ByVal e As EventArgs)
MyBase.OnLoad(e)
CopyBtn.Text = "Copy File"
CopyBtn.Parent = Me
ProgBar.Left = CopyBtn.Right
End Sub
Dim WithEvents CopyBtn As New Button
Dim ProgBar As New ProgressBar
Dim WithEvents FileCopier As New WebClient
Public Sub check(ByVal sender As Object, ByVal e As EventArgs) Handles CopyBtn.Click
Dim src As String = "D:\test"
Dim dest As String = "D:\test2"
For Each Dir As String In System.IO.Directory.GetFiles(src)
Dim dirInfo As New System.IO.DirectoryInfo(Dir)
If Not System.IO.File.Exists(dest & "\" & dirInfo.Name) Then
filesToCopy.Add(dirInfo.Name)
End If
Next
If filesToCopy.Count > 0 Then
If MsgBox("There are new files found. Do you want to sync it now?", MsgBoxStyle.Question + MsgBoxStyle.YesNo, "Confirm") = MsgBoxResult.Yes Then
For i = 0 To filesToCopy.Count - 1
Dim FileCopier As WebClient = New WebClient
AddHandler FileCopier.DownloadProgressChanged, AddressOf FileCopier_DownloadProgressChanged
AddHandler FileCopier.DownloadFileCompleted, AddressOf FileCopier_DownloadFileCompleted
CopyBtn.Enabled = False
ProgBar.Parent = Me
FileCopier.DownloadFileAsync(New Uri(src & "\" & filesToCopy(i)), dest & "\" & filesToCopy(i))
Next
End If
Else
MsgBox("No new files to be copied")
End If
End Sub
this is my code that tracks the number of files copying.
Private Sub FileCopier_DownloadProgressChanged(ByVal sender As Object, ByVal e As DownloadProgressChangedEventArgs) Handles FileCopier.DownloadProgressChanged
ProgBar.Value = e.ProgressPercentage
For Each file In filesToCopy
total += filesToCopy.Add(file)
Next
Label2.Text = total \ filesToCopy.Count
End Sub
End Class

Answer 1

Add it here instead in DownloadProgressChanged
For i = 0 To filesToCopy.Count - 1
Dim FileCopier As WebClient = New WebClient
AddHandler FileCopier.DownloadProgressChanged, AddressOf FileCopier_DownloadProgressChanged
AddHandler FileCopier.DownloadFileCompleted, AddressOf FileCopier_DownloadFileCompleted
CopyBtn.Enabled = False
ProgBar.Parent = Me
FileCopier.DownloadFileAsync(New Uri(src & "\" & filesToCopy(i)), dest & "\" & filesToCopy(i))
Label2.Text = i + 1 & "/" & FilesToCopy.Count 'PUT IT HERE INSTEAD
Next