System.NotSupportedException when trying to create an asset

I was able to create a working demo using a .NET 4.6.1 and following nuget package:

• windowsazure.mediaservices v3.6.0.0

  1. Create a brand new MVC app.
  2. Add some dependency assemblies in web.config (if doesn't exists) https://social.msdn.microsoft.com/Forums/azure/en-US/eb05a115-36b2-47a5-b464-3220548a5de9/upgrade-to-media-services-sdk-20-error-with-microsoftpracticestransientfaulthandlingcore?forum=MediaServices
  3. Add a post action

[HttpPost]public async Task<string> PostUpload(){    var bytes = System.Text.Encoding.UTF8.GetBytes("Test");    var data = new VideoData { Data = bytes };    CloudMediaContext _context;    using (MemoryStream ms = new MemoryStream(data.Data))    {        var accountName = "accountName";        var accountKey = @"primaryaccessKey";        _context = new CloudMediaContext(accountName, accountKey);        var asset = await _context.Assets.CreateAsync("myjblobassets", AssetCreationOptions.None, CancellationToken.None);        //... do something with asset and ms ...    }    return "http://my-link";}

* Note: any bytes is fine here since we are not demonstrating the upload part, we are making sure creating a Media Service Asset works.

4. Add a HTML form and submit button in the index view pointing to this post action, run it and works!!!

Note: In NAME, enter the name of the new account. A Media Services account name is all lower-case numbers or letters with no spaces, and is 3 - 24 characters in length. https://azure.microsoft.com/en-us/documentation/articles/media-services-dotnet-get-started/

I can't tell you why it's not working exactly.But i think the problem is more likely to find in the construction of your function than in the Azure API.

It should be done like this:

    // Important is the return value of the function:     public async Task<IAsset> CreateAssetBlobAsync(CancellationToken token)    {                    var asset = await _context.Assets.CreateAsync("blobContainerName", AssetCreationOptions.None, CancellationToken.None); // or your 'token'        return asset;    }

And this async function should be called like this:

public static async Task ProcessNewBlobAsync(){     // ...     var asset = await CreateAssetBlobAsync(token);     // ...}

I think the problem will be your using Statement.

Fact is the Read/Write Async methods of MemoryStream don't actually provide any kind of true asynchronous implementation. Which means they always will be synchronously.

(But you didn't call any of them. I fear maybe it will be a synchronous wrapper for the async method. And so it will call the API synchronous instead of asynchronous. This is only a thought.)

I recommend to avoid using-Statements with async for preventing a deadlock.

I hope that "blobContainerName" is a mock you wrote when posting the question? Capital letters and blob containers do not mix :)