Quick Tip: Could not load file or assembly System.Web.Silverlight.dll

Had a collegue of mine who was working with the Silverlight Blueprint for SharePoint and after installing one of the examples, received a Server Error.

At first he could not view the error message, so I had my collegue turn on debugging.  After this, he was able to view the error properly.

The error was:

Parser Error Message: Could not load file or assembly ‘System.Web.Silverlight, Version….’or one of its dependencies. The system cannot find the file specified.

There’s a simple solution to this error message, so I thought I’d also post it here for everyone.

Solution

1. Copy System.Web.Silverlight.dll from C:\Program Files\Microsoft SDKs\Silverlight\v2.0\Libraries\Server to C:\Windows\assembly
2. Copy Silverlight.js from C:\Program Files\Microsoft SDKs\Silverlight\v2.0\Tools to C:\inetpub\wwwroot\wss\VirtualDirectories\<portNumber>\ClientBin\
3. Register Silverlight MIME type for file extension .XAP in IIS
4. Reset IIS

This solved my collegue’s problems and hopefully helped you out.