After I install Silverlight 3 Tools for Visual Studio 2008, I started a new Silverlight Application Project.

When I try to run this default project, I get this error:

Error: Unhandled Error in Silverlight Application Code: 2104

Category: InitializeError

Message: Could not download the Silverlight application. Check web server settings

What is the problem?

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 Hi,

The error maybe due to MIME types. You will have to add the following MIME types:

.xaml    application/xaml+xml 
.xap    application/x-silverlight-app 
.xbap    application/x-ms-xbap 

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 網頁放上虛擬空間瀏覽時發生錯誤訊息

Unhandled Error in Silverlight Application

code:2104

category:initializeError

此訊息為虛擬空間IIS無法辨識此副檔名(.xap).....
解決方式與實體Server大同小異(虛擬空間無法直接操控IIS)

Plesk後台設定
Domain > Web Directories > MIME Types > Add New MIME Type >

Extension : .xap 
Content : application/x-silverlight-app