Some developers reported to us they were experiencing StackOverflowException when using SlSvcUtil.exe that shipped with the SL4 SDK. Upon investigation, we discovered that this happens on machines with a system language set to something else than US English.
Fortunately, this can be fixed neatly by using an application configuration file. Create a file named SlSvcUtil.exe.config that you will place within the same directory as the tool. Populate the file with the content below.
<assembly name="SlSvcUtil, Version=126.96.36.199, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
This instructs the .NET4 runtime ResourceManager that SlSvcUtil.exe is “culture neutral”, which will bypass the satellite resource lookup that was the root of the failure.
Now, when you reuse the tool, it should work as expected.
Developer, Silverlight WCF Team