AjaxFileUpload reloads page on upload ONLY for image files - asp.net

Question

I have been working to debug an intermittent issue I've been experiencing with AJAXFileUpload. I'm moving our code away from another uploader and have worked this into several pages already. I have realized that the uploader is reloading the page after completing the UploadComplete code in the code-behind ONLY for images. I can upload .pdf, .docx with absolutely no problem but as soon as I try .png, .jpeg, .gif, etc the page reloads immediately after the upload.
I can't find anything that would suggest the behavior between these two types of files should be different and I'm assuming I'm missing something.
Here is my upload control:
<ajax:AjaxFileUpload AutoStartUpload="true" OnClientUploadCompleteAll="() => $('#btnSaveThumbnails').toggle()" ClientIDMode="Static" style="max-width:800px;display:none" runat="server" ID="thumbUploader" />
And here is the code-behind for the UploadComplete function:
If Not System.IO.Directory.Exists(tempFilePath) Then
System.IO.Directory.CreateDirectory(tempFilePath)
End If
sender.SaveAs(tempFilePath & e.FileName)
Session("docUploaderFiles") = If(Session("docUploaderFiles"), New List(Of String))
CType(Session("docUploaderFiles"), List(Of String)).Add(e.FileName)
Like I mentioned, these work exactly as expected for non-image file types in my experience.
UPDATE: I have narrowed it down to being caused by the .SaveAs call in the code-behind. Removing just that line causes no page reload.
UPDATE: I have found this issue is specific to my machine. The uploader works on other local environments as well as on our production application. Possibly something to do with my IIS.

Answer 1

I can't see why this would not work.
However, I have OFTEN found that if you don't specify and wire up the CLIENT side events, then the up-loader can barf on you.
So, try this for your test:
<ajaxToolkit:AjaxFileUpload ID="AjaxFileUpload1" runat="server"
OnClientUploadComplete="MyComplete"
OnClientUploadCompleteAll="MyCompleteAll"
OnClientUploadStart="MyStart" AllowedFileTypes="txt,zip,png,jpeg"
OnClientUploadError="MyError" ChunkSize="16384" />
</div>
<br />
<br />
</div>
<script>
function MyStart() {
}
function MyComplete() {
}
function MyCompleteAll() {
}
function MyError(e) {
}
</script>
Note how I added the client side events. I have found in some cases that without the client side events, then problems arise, so I drop in the 4 blank client side events.
EVEN if you not using the client side events, try putting them in as per above. So, I dropped in 4 client side events - without any code in those stubs.
My server side code for this test is this:
Protected Sub AjaxFileUpload1_UploadCompleteAll(sender As Object, e As AjaxControlToolkit.AjaxFileUploadCompleteAllEventArgs) Handles AjaxFileUpload1.UploadCompleteAll
Debug.Print("all done")
End Sub
Protected Sub AjaxFileUpload1_UploadStart(sender As Object, e As AjaxControlToolkit.AjaxFileUploadStartEventArgs) Handles AjaxFileUpload1.UploadStart
Debug.Print("start upload")
End Sub
Protected Sub AjaxFileUpload1_UploadComplete(sender As Object, e As AjaxControlToolkit.AjaxFileUploadEventArgs) Handles AjaxFileUpload1.UploadComplete
Debug.Print("file done")
Debug.Print(e.FileName)
End Sub
Protected Sub AsyncFileUpload1_UploadedFileError(sender As Object, e As AjaxControlToolkit.AsyncFileUploadEventArgs)
Debug.Print(e.StatusMessage)
End Sub
I would also check + clear out non ASCII chars in the file name. I seen funny files - and they blow out a error.
So, I do this:
Dim strCleanFile As String = TrimNonAscii(e.FileName)
and
Public Function TrimNonAscii(ByVal value As String) As String
Dim pattern As String = "[^ -~]+"
Dim reg_exp As Regex = New Regex(pattern)
Return reg_exp.Replace(value, "")
End Function
So I trim out spaces, and also rip out other funny values. (from a Mac or other devices, they actually allow non legal windows chars in the file name, but windows does not.