I was recently working on a project that used WCF web services extensively. Everything was ready for deployment, I deployed to the remote host, and voila – nothing works (nothing WCF related). After a LOT of frustration, I managed to make it work. I found two areas which were causing the problem:

1. The .svc extension was NOT setup right at our host. You can set this in the web.config webhandlers section for IIS 7, but not for IIS 6.0. I had IIS 7, but decided to bug my host to set up the extension on the server ;)

2. I had multiple host headers; i.e. my site worked for both http://mysite.com and http://www.mysite.com. To resolve this issue, you can either disable all but one if your host permits. Otherwise, you need to use a factory. Here’s an example of such a factory:

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Web; 
using System.ServiceModel; 
using System.ServiceModel.Activation;

namespace Shipping.WebService 
{ 
    public class MultipleIISBindingSupportServiceHostFactory : ServiceHostFactory 
    {

        protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses) 
        {

            Uri[] requiredAddress = GetAppropriateBase(baseAddresses);

            return base.CreateServiceHost(serviceType, requiredAddress);

        }

        Uri[] GetAppropriateBase(Uri[] baseAddresses) 
        { 
            List<Uri> retAddress = new List<Uri>(); 
            retAddress.Add(baseAddresses[0]);

            return retAddress.ToArray();

        }

    }

}

Granted, it can be way more efficient and you can do nifty tricks with the url to support both http:// and http://www, but I can happy to have just one for my webservice.

Next, you need to set the factory in the markup of the ,svc file. You can do it like this:

<%@ ServiceHost Language="C#" Debug="false" Factory="Shipping.WebService.MultipleIISBindingSupportServiceHostFactory" Service="Shipping.WebService.ClientService" CodeBehind="ClientService.svc.cs" %>

Hope that helps.