We have created a KB article where a possible approach to achieve image resizing before the upload is suggested. You can find it at https://www.telerik.com/support/kb/aspnet-ajax/upload-(async)/details/resize-images-client-side-with-html5-before-uploading-with-radasyncupload

The article describes a straightforward way on how to change the uploaded image dimensions. You can further improve and modify the logic in the _uploadFile function to allow the user to define the new dimensions or use a tool to allow the users to modify the image.

When upload larger files the connection may dropped during the file uploading. In result of this the selected file will not be uploaded successfully and the user will have to start the uploading from the beginning. This operation can be very annoyng when connection is slow. 

The suggested features aims to allow resuming, when the failed file is selected again. The uploading should continue automatically from there it stopped.

We would like to upload a folder's structure and content via asyncupload drag and drop functionality.  This functionality exists with Chrome and FireFox now.  Please add.  Thanks.

 RadAsyncUpload does not upload files in iOS 8 Safari. After selecting a file/files for upload, their upload remains as pending and never reaches the end of the process.
Note: there is a known iOS 8 Safari issue with <input type="file" />

I am using the RadAsyncUpload with UploadedFilesRendering="BelowFileInput".  This works fine, but I would like the list to appear in the order they are selected not the reverse order.  Is there away to accomplish this?  It should look like the UploadedFilesRendering="AboveFileInput" list but appearing below.

This should be a feature of the control which currently limited to above in the order they are select or below the reverse order.  In either case you should be able to select the order the files are displayed in the UI.

Currently the AsyncUpload saves the chunks in the Temporary folder using the original name of the file, the Process method of the Custom handler. When the Temporary folder name is very long, it can hit the Windows path length limitation of 260 symbols.

Workaround: 

function encodeRowContent() {
    var asyncUpload = $find('<%= RadAsync_FileUpload.ClientID%>');
    var $ = $telerik.$;
    asyncUpload._updateRowContent = function (row, inputValue) {
        var $progress,
            $content = $("<span class='ruUploadProgress'>" + $telerik.htmlEncode(this._getFileName(inputValue)) + "</span>");

        $(row).removeClass("ruSelectWrap")
                .addClass("ruFileLI ruUploading")
                .prepend("<span class='radIcon'></span>");

        if (this._isManualUpload())
            $content.addClass("ruUploadOnHold");

        if (this._enableInlineProgress) {
            $progress = $('<span class="ruFileProgressWrap"><span class="ruFileProgress"></span></span>');
            $content.append($progress);
        }

        $('.ruFakeInput, .ruBrowse', row).remove();
        $(".ruFileWrap", row).append($content); // Replace fake input
    }
}

Sys.Application.add_load(encodeRowContent);

I would be nice to gain more control over radasyncupload's upload behavior when using database as storage for uploaded files.

Consider this use case. You have file management web-app that uses SQL database as storage for uploaded files. In SQL database you use Filestream enabled table to store the uploaded file data. You like to allow your app users to upload multiple big files > 100 Mt at once. And you have limited disc space on your web server hosting your app. So you don't want to buffer those uploaded files on your web server in any point of the upload process.

To be able to do so radasyncupload needs to be able to stream uploaded files to the SQL database as straight as possible. Chunk by chunk. 

radasyncupload already has feature that allows you to use your own generic handler to handle some of the upload process. It just needs expose some of those events that happens before process-event (maybe ProcessRequest?). So developer can start handling the HttpPostedFile's InputStream at the begining of the upload and stream it directly to the database. Like one can do with the regular upload controls like so:

Public Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest

	Dim hpf As HttpPostedFile
	
	For i = 0 To context.Request.Files.Count - 1
	
		hpf = context.Request.Files.Item(i)
		
		...
		Using Command As SqlCommand = New SqlCommand(String.Concat("INSERT INTO Dokuments(DokumData...) values (@DokumData...)"), connection)
		'Other params

		Command.Parameters.Add("@DokumData", SqlDbType.Binary, -1).Value = hpf.InputStream
		connection.Open()
		Command.ExecuteScalar()
		connection.Close()
		
	Next

End Sub

RadAsyncUpload "Drop Files here" element remains visible when dragging a file quickly over and out of the DragZone

Replicable in File Upload with Drag and Drop live demo.

Drag a file quickly through the DragZone without dropping it. The "Drop Files Here" element is shown but doesn't get hidden when the mouse leaves the DragZone (ondragleave).

The user should be able to determine by which criteria the validation failed (size or extension).

Here's the scenario: 
User changes the extension of a .js file to .jpg and upload the file, by no means we are able to restrict the user from uploading the file. 
Is there a way to stop user from uploading based on associated mimetype ?

Hi Telerik Team,
is it possible to implement the feature into the uploadmodule control , that you can open the uploaded files per Double-Click.
We want to use the control to create offers and we want to give the users the option to upload files - that works wonderful.
But the following editors of the offers don`t have the chance to open the "attached" files.

Thank you very much.
Best Regards,

Jan Brandenburger

The MaxFileSize property is an int - this means a limit over 2GB can't be set. Please change this property to a long.