Why Can’t I "Go Live" with Silverlight 1.1 Alpha?

I just wanted to clarify something that is hopefully already pretty well understood. As folk know, we released an alpha of Silverlight 1.1 at MIX, and there are lots of people who would love to use it even in its current form. It's great to see the excitement around using .NET for web development, of course, but Silverlight 1.1 (now known as 2.0) is not ready for "Go Live" usage at this stage, and the EULA explicitly prohibits deployment in production sites.

Why is this? Primarily it's because the currently-available 1.1 bits were produced very early in the development milestone, and they are not being actively serviced. If you have Silverlight 1.1 on your machine, the latest version you are likely to have is 1.1.20926.0 (where the last four digits of the build number indicate that this build was compiled on 09/26, i.e. September 26th). We actually shipped a maintenance release a couple of weeks ago for 1.0 (build 1.0.21115.0), but we're not attempting to keep the 1.1 alpha build in sync with this. (Hey, it's a developer preview build!)

The net impact of that is that if you have the 1.1 alpha on your machine, you may find that some 1.0 sites won't load successfully on your machine (in their manifest, they may require the maintenance release as a minimum build number). This shouldn't be an issue for any consumer in the "real world" - it's purely something that will affect a developer who is living at the bleeding edge by installing alpha software on their machines.

And that’s why we’re not clearing 1.1 for "Go Live" / production usage at this stage – we don’t want it to be broadly deployed. It's not fair for us or anyone else to inflict alpha-quality software on their customer base to view a website! We'll have a solution here by MIX, but I hope this explains the intent behind the current licensing.

Comments (9)

  1. Anonymous says:

    Thanks for the clarification, but when is a go live version expected?

  2. imranshaik says:

    Hi Tim,

    Just a quick question, will Silverlight 2.0 plug-in have backward compatibility with Silverlight 1.1A applications?


  3. Anonymous says:

    Hi Tim,

    I have been learning Silverlight/WPF and was very disappointed to realise the 3d view port has not been included in Silverlight.

    I’m not sure how but I would like to encourage the Silverlight team to include the viewPort3d in the final realise, even if it’s an optional add-on or only available to developers for the time being.

    I have noticed that when I open 3d xaml in a browser directly the 3d does work as I wish it too. However as we know, when added to a html,.aspx page etc the browser will not accept. Is there a work around here for the purpose of test/development?

    Many thanks.

  4. Tim Sneath says:

    Some good questions.

    Michael, we’ll have a limited form of Go Live license in time for MIX – still locking down details of that right now.

    Imran, there are substantial breaking changes between the 1.1 alpha and what will become the final 2.0 release – we don’t claim to be backward compatible with 1.1 alpha. However, 2.0 _is_ fully backward-compatible with 1.0 applications.

    Rich, we don’t support the 3D graphics APIs in Silverlight. This is a premium WPF feature that relies on the underlying DirectX hardware accelerated GPU support. If you want 3D, then WPF is your best choice. When you open a .xaml file in a browser, it’s WPF that’s being loaded, rather than Silverlight. You can host WPF content in an HTML page by creating a "XAML Browser Application", known as XBAP for short – but note that of course WPF is Windows-only. Hope this clarifies.

    Best wishes,


  5. Anonymous says:

    Thanks for blogging this, Tim.

    Vertigo recently released Slide.Show — a Silverlight 1.0 slideshow control that has been impacted by this.

    Slide.Show works perfectly in Firefox provided you are using the Silverlight 1.0 update that came out last month, but unfortunately, early adopting devs with the Silverlight 1.1 Alpha installed aren’t getting the 1.0 auto-update (and not realizing it), so I keep having to field the question "Why doesn’t Slide.Show work in Firefox"? Sigh. Oh well.

    Here’s a thread that discusses our particular issue:


  6. Cox, Ken says:

    It seems nobody has told these guys there’s no Go Live for 1.1


    The examples try to install the Alpha.

  7. Anonymous says:

    Merry Christmas from SilverlightCream — Here's a whole bunch of things that found it's way into

  8. Anonymous says:

    You may have noticed that I stopped putting Silverlight 1.1 code out on my blog and stopped talking about

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