Silverlight 2 applications: a day after Silverlight 3 release

June 16, 2009

Silverlight 3 release date is approaching, and I’m getting questions what will happen to existing Silverlight 2 applications after it will be released. Also I’m getting questions about the runtime version upgrade.

Let’s see what will happen after Silverlight 3 will be released…

Those who already using Silverlight 2 and getting automatic updates will receive the new runtime automatically. Everyone else need to download and install it manually.

The updated clients will be able to run Silverlight 2 applications as it was before the runtime update. It is possible because of “quirk mode change” – the special mode, that will not enforce Silverlight 3 runtime/features if the runtime detects that the application being run was designed for Silverlight 2. In this way, Silverlight 3 is made “bug compatible” with Silverlight 2 when a Silverlight 2 application is being run (i.e. all bugs from original Silverlight 2 will occur, even if Silverlight 3 already fix them). This will happen until the developers will not compile the application with Silverlight 3 runtime.

Actually, the detection made by querying the “RuntimeVersion” attribute in AppManifest.xml: “RuntimeVersion” reflects the build of Silverlight that was on the developer’s machine when the application was compiled. Thus, if Silvelright 3 runtime will detect for example RuntimeVersion="2.0.31005.0" (Silverlight 2 RTW version) it will execute the application in “quirk mode”, if “RuntimeVersion” will be Silverlight 3 version the application will work in full Silverlight 3 mode.

Now the quick tip for those, who developed Silverlight 2 application:

While updating Silverlight 2 application to use version 3 make sure that you also update update the new “minRuntimeVersion” attribute to the Silverlight 3 ones to ensure the end-user has the correct version.


Stay tuned for more updates/tips


Add comment
facebook linkedin twitter email

Leave a Reply

Your email address will not be published.

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>



  1. Jonathan van de VeenJune 18, 2009 ב 9:39

    Thanks! That is very useful to us, as we are in full swing developing our enterprise application in SL2 and are not in the position to move to SL3 right away.

  2. Alex GoleshJune 19, 2009 ב 7:25

    Jonathan van de Veen: You should consider moving to SL3 because many additions/improvements for LOB 🙂
    Anyway, I think it is worth trying to recompile vs SL3 runtime (once it will be released) to see how far you are from the SL3 application and the decide. Maybe you are not so far as you think now 😉