Access is denied error on every script second run on his own folder

Access is denied

$FTPHost = 'someserver'
$FTPUser = 'someuser'
$FTPPass = '*******'
$srcFolder = "D:\testUploadData"
$destPath = 'testFolder'
 
 
$destTmpPath = "${destPath}.TMP"
$destOldPath = "${destPath}.OLD"
 
try {
    # Load WinSCP .NET assembly
    Add-Type -Path (Join-Path $PSScriptRoot "..\winscp_assembly\WinSCPnet.dll")
 
    $sessionOptions = New-Object WinSCP.SessionOptions -Property @{
        Protocol = [WinSCP.Protocol]::Ftp
        HostName = $FTPHost
        UserName = $FTPUser
        Password = $FTPPass
    }
 
    $session = New-Object WinSCP.Session
    $session.SessionLogPath = 'log.txt'
 
    try {
        Write-Host("Connecting to FTP")
        $session.Open($sessionOptions)
        
        Write-Host("Creating .TMP dir")
        if($session.FileExists($destTmpPath)) {
            $session.RemoveFiles($destTmpPath).Check()
        }
 
        $session.CreateDirectory($destTmpPath)
        
        Write-Host("Uploading to .TMP dir")
        $session.PutFiles($srcFolder, $destTmpPath).Check()
        
        Write-Host("Renaming live dir to .OLD")
        if(!$session.FileExists($destPath)) {
            $session.CreateDirectory($destPath)
        }
 
        if($session.FileExists($destOldPath)) {
            $session.RemoveFiles($destOldPath).Check()
        }
        
        $session.MoveFile($destPath, $destOldPath)
 
        Write-Host("Renaming .TMP dir to live")
        $session.MoveFile($destTmpPath, $destPath)
        
        Write-Host("Removing .OLD dir")
        $session.RemoveFiles($destOldPath).Check()
    }
    finally {
        $session.Dispose()
    }
 
    exit 0
}
catch {
    Write-Host "Error: $($_.Exception.Message)"
    exit 1
}