"The size of the uploaded file exceeds max size allowed" is thrown even if the file is under the specified maximum upload file size.

The error is reproducible in the Default demo -> http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx.

Open the Document manager and upload some unsupported file which size does not exceed 200 kb. For example upload a small image file. You'll get the following error:

The size of the uploaded file exceeds max size allowed.
The extension of the uploaded file is not valid. Please, provide a valid file!

while only this line should be shown: The extension of the uploaded file is not valid. Please, provide a valid file!