SharePoint Designer 2010 – The server could not complete your request. The content type of the response is "".

Last night I came across an interesting problem, a SharePoint Server 2010 site that I am hosting on a Beta 2 server was having issues connecting via SharePoint Designer 2010.  A colleague brought my attention to it, and the very unhelp error messages that were being displayed, with no events in the event log on his PC.

He reported that the initial connection from SharePoint Designer 2010 appeared to be okay, however soon after being established the following error would occur:

This was very odd as the previous server this site had resided on had had no problems at all.  My first thought was that this must be an authentication issue, and I immediately tried switching from Claims Based Authentication back to Classic Authentication.  This had no effect on the problem.

I then cranked up the logging on the server, cleared the event logs and tried to make a connection again and the following came up almost immediately : 

 WebHost failed to process a request.
 Sender Information: System.ServiceModel.ServiceHostingEnvironment+HostingManager/59487907
 Exception: System.ServiceModel.ServiceActivationException: The service '/_vti_bin/client.svc' cannot be activated due to an exception during compilation.  The exception message is: This collection already contains an address with scheme http.  There can be at most one address per scheme in this collection.
Parameter name: item. —> System.ArgumentException: This collection already contains an address with scheme http.  There can be at most one address per scheme in this collection.
Parameter name: item
   at System.ServiceModel.UriSchemeKeyedCollection.InsertItem(Int32 index, Uri item)
   at System.Collections.Generic.SynchronizedCollection`1.Add(T item)
   at System.ServiceModel.UriSchemeKeyedCollection..ctor(Uri[] addresses)
   at System.ServiceModel.ServiceHost..ctor(Type serviceType, Uri[] baseAddresses)
   at System.ServiceModel.Activation.ServiceHostFactory.CreateServiceHost(Type serviceType, Uri[] baseAddresses)
   at System.ServiceModel.Activation.ServiceHostFactory.CreateServiceHost(String constructorString, Uri[] baseAddresses)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.CreateService(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.ActivateService(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath)
   — End of inner exception stack trace —
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.EnsureServiceAvailableFast(String relativeVirtualPath)
 Process Name: w3wp
 Process ID: 6116
 

Fortunately this error is a fairly well known and documented WCF problem, and a quick search came up with this : http://social.msdn.microsoft.com/Forums/en-US/wcf/thread/9e248455-1c4d-4c5c-851c-79d9c1631e21/#page:1 

The short version?  WCF only supports one binding per IIS Web Site.  This can obviously be a problem where multiple host header bindings are required on the same IIS web site.  

The easy way around this?  Add another IP to your webserver, and setup a wildcard IP binding on that IIS site.  Then update your name server to point to the new IP address.  Host Header requests will still work fine as SharePoint will use its own internal Host Header Filter to discern which site to send each request to.   There are other work arounds so that you can have multiple bindings, but you will probably have to hack a bit to get them working.  Go seaching at your own peril 🙂

While this particular issue only presented itself on SharePoint Designer at first, upon closer inspection I found that other services, such as my Search Service Application, Tag Cloud, Multiple File Upload, etc were not working at all.  I would imagine best practices would be to always only use a single binding on each IIS website on your SharePoint 2010 servers.

To quote the colleague who brought it to my attention "It is a major thing and I pity the fool that thinks he can have http://intranet and http://intranet.company.com on the same web app ;o)".  Well said.