[Solved] File Move Error: Cannot create a file when that file already exists

Hello kana250688,

First you need to save the file in diffrent name and delete the old one.

Please refer the below codes.

Code

C#

 protected void Page_Load(object sender, EventArgs e)
 {
     Dictionary<string, string> files = new Dictionary<string, string>();
     files.Add("Sample.docx", "Sample.docx");
     files.Add("Sample.pdf", "Sample.pdf");
     files.Add("Sample.xlsx", "Sample.xlsx");
     RenameFiles(files, Server.MapPath("~/Files"));
 }
 private void RenameFiles(Dictionary<string, string> fileNameMapper, string path)
 {
     DirectoryInfo dir = new DirectoryInfo(path);
     IEnumerable<FileInfo> files = dir.EnumerateFiles().Where(fi => fileNameMapper.ContainsKey(fi.Name));
     foreach (FileInfo file in files)
     {
         string oldPath = Path.Combine(file.Directory.FullName, fileNameMapper[file.Name]);
         string newPath = Path.Combine(file.Directory.FullName, (DateTime.Now.Ticks + "_" + fileNameMapper[file.Name]));
         if (File.Exists(oldPath))
         {
             file.MoveTo(newPath);
             File.Delete(oldPath);
         }
     }
 }

VB.Net

Protected Sub Page_Load(sender As Object, e As EventArgs)
    Dim files As Dictionary(Of String, String) = New Dictionary(Of String, String)()
    files.Add("Sample.docx", "Sample.docx")
    files.Add("Sample.pdf", "Sample.pdf")
    files.Add("Sample.xlsx", "Sample.xlsx")
    RenameFiles(files, Server.MapPath("~/Files"))
End Sub

Private Sub RenameFiles(fileNameMapper As Dictionary(Of String, String), path As String)
    Dim dir As DirectoryInfo = New DirectoryInfo(path)
    Dim files As IEnumerable(Of FileInfo) = dir.EnumerateFiles().Where(Function(fi) fileNameMapper.ContainsKey(fi.Name))
    For Each file As FileInfo In files
        Dim oldPath As String = IO.Path.Combine(file.Directory.FullName, fileNameMapper(file.Name))
        Dim newPath As String = IO.Path.Combine(file.Directory.FullName, (DateTime.Now.Ticks & "_" + fileNameMapper(file.Name)))
        If IO.File.Exists(oldPath) Then
            file.MoveTo(newPath)
            IO.File.Delete(oldPath)
        End If
    Next
End Sub

Screenshot