The slsvcutil tool crashes when Silverlight 5 is installed

This article helps you resolve an error that may be thrown when you use the slsvcutil.exe command line tool to generate a proxy for Windows Phone.

Original product version:   Silverlight 5
Original KB number:   2694961

Symptoms

When you attempt to use the slsvcutil.exe command line tool to generate a proxy for Windows Phone, you get an error that looks like:

Error: An error occurred in the tool.
Error: Could not load file or assembly C:\Program Files (x86)\Microsoft Silverlight\5.0.61118.0\System.Runtime.Serialization.dll or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded.

Cause

It's caused if the developer has the Windows Phone SDK 7.1 and Windows Phone SDK 7.1.1 Update and Microsoft Siliverlight 5 installed on the developer computer. Silverlight 5 changes a registry key that slsvcutil relies on to determine which assemblies to load.

Resolution

The fix is to explicitly use a config file to specify the supported runtime version. The developer should supply a config file alongside the actual slsvcutil.exe file in the Windows Phone 7.1 tools folder (for example, C:\Program Files (x86)\Microsoft SDKs\Windows Phone\v7.1\Tools). This config file should be named slsvcutil.exe.config and should have the following contents:

<?xml version ="1.0"?>
<configuration>
    <startup>
        <supportedRuntime version="v4.0"/>
        <supportedRuntime version="v2.0.50727"/>
    </startup>
</configuration>

After ensuring a file with these contents with the name slsvcutil.exe.config are in the same directory as slsvcutil.exe, then invoking slsvcutil.exe should work properly.