2104 Couldn't download the silverlight application

Error:

2104 无法下载 Silverlight 应用程序。检查 Web 服务器设置

2104  Couldn't download the silverlight application. Check web Server Settings.

Silverlight Error #2104 Could not download the silverlight application in IIS6

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If you receive this error while trying to deploy your Silverlight application, make sure you did the following things:  
1. Adjust the Content Expiration Setting

You should adjust the content expiration setting to 1 minute. The following procedure outlines how to do this with IIS.

1. Right-click  your Web Site and select Properties from the context menu.

2. Select the HTTP Headers tab and click "Enable Content Expiration".

3. Set the content to expire after 1 minute.

2. Register MIME Types and File Extensions

You must register some MIME types and file extensions so that the browser on the client's system can load the correct handler. You need to add the following types:

Extension	MIME Type
.xap	application/octet-stream
.xaml	application/xaml+xml

The .xap needs to have that mime type, in order to be able to be downloaded.

3. Execute permissions must be Scripts Only.

1. Right-click  your Web Site and select Properties from the context menu.

2. Select the Directory tab and change "Execute Permissions" to Script only.

 
Hope this helps. 

 

http://silverlight.net/forums/p/20037/70756.aspx#70756