Ability to upload files to Azure Blob Storage CustomUploadHandler-AzureUpload demo is added in our SDK: https://github.com/telerik/xaml-sdk/tree/master/Upload/CustomUploadHandler-AzureUpload
Currently there is no way to pass parameters in the FileUploadFailedEventArgs of the FileUploadFailed event. In the UploadCompleted event such parameters are passed in the HandlerData.CustomData of the FileUploadedEventArgs. Available in LIB version: 2014.3.1402
Available in R2 2016 Release
The last response of contains incorrect information (it contains data from the previously uploaded chunk). Available in LIB version: 2016.3.1010