File Extension Validation

Demo uploads land in a temporary store and are swept after 60 minutes. To keep files, handle FileUploaded — see Single File for the complete save pattern.

Restrict uploads to specific file types using AllowedExtensions. Only files with matching extensions will be accepted. Files that don't match are rejected with a message.

What you should see: only .jpg/.png/.gif are accepted; anything else is refused immediately with no request made.

Images Only (.jpg, .png, .gif)

Drag & drop files here, or paste from clipboard

<%@ Register Assembly="AjaxUploader" Namespace="AjaxUploader.Controls" TagPrefix="au" %>

<au:AjaxFileUpload ID="Uploader1" runat="server"
 AllowedExtensions=".jpg,.png,.gif"
 ButtonText="Select Image"
 AutoUpload="true"
 ShowProgress="true" />

Try selecting a .txt or .pdf file to see the validation error.