@Marko - The files are uploading on chunks because the maximum request in ASP.NET is 4MB and if the request exceeds this value an exception is thrown. To avoid that behavior you need to set request length from your web config (which we want to avoid).
1. It is possible only to access the Process method (after the file is assembled). There is no event or method to access the uploading chunks.
2. If you are overriding the Process method, you need to call the base if you want the uploaded files to be deleted automatically after a certain time.
3. We do not support custom progress handler.
@Yuriy - if you want to limit the uploading file size you can use the MaxFileSize
All the best,
the Telerik team
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