FileUpload.PostedFile always null inside UpdatePanel

Question

I have a FileUpload control inside an UpdatePanel. I have successfully registered the upload button with the scriptmanager to do a full postback. The only issue I have is that FileUpload.HasFile is always returning null. Note: When I move the FileUpload control outside of the updatepanel everything works file. Is there a solution or workaround for this.

Thanks.

Answer 1

You can put a FileUpload control in an UpdatePanel but you have to use a PostBackTrigger as opposed to an AsyncPostBackTrigger. I recently used this approach and combined both types of trigger.

    <Triggers>
        <asp:PostBackTrigger ControlID="btnSave" />
        <asp:AsyncPostBackTrigger ControlID="btnAsyncSave"/>
    </Triggers>

The PostBackTrigger was used for FileUploads while the AsyncPostBackTrigger was used for all the other form fields.

Answer 2

FileUpload doesn't work inside an UpdatePanel. You must use AsyncFileUpload from ASPNET AJAX control Toolkit.

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When you use AsyncFileUpload you must set the right params in the form tag, that is placed in your Page or MasterPage:

<form id="form1" runat="server" enctype="multipart/form-data" method="post">

If you don't set the right enctype and method UploadedComplete will never fire, and you won't be able to get FileUpload.FileBytes since FileUpload.HasFile returns true only during UploadedComplete execution.

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Besides, prevoius versions of AsyncFileUpload didn't work on Chrome. Actual version (4.1.50731.0) solved the problem.