[.net] WCF service startup error "This collection already contains an address with scheme http"

I built a web application containing a WCF service contract and a Silverlight control which makes calls to that WCF service. On my development and test servers it works great.

When I deploy to our live server and run the application I get an exception of type System.ServiceModel.ServiceActivationException which states that the service can not be activated due to an exception during compilation. The exception is:

This collection already contains an address with scheme http. There can be at most one address per scheme in this collection.

I read that this exception may be thrown if the web site has more than one host header, which is true on our live server. Apparently WCF services hosted in IIS can have only one base address. How can I get around this issue?

I had this problem, and the cause was rather silly. I was trying out Microsoft's demo regarding running a ServiceHost from w/in a Command Line executable. I followed the instructions, including where it says to add the appropriate Service (and interface). But I got the above error.

Turns out when I added the service class, VS automatically added the configuration to the app.config. And the demo was trying to add that info too. Since it was already in the config, I removed the demo part, and it worked.

I came by the same error on an old 2010 Exchange Server. A service(Exchange mailbox replication service) was giving out the above error and the migration process could not be continued. Searching through the internet, i came by this link which stated the below:

The Exchange GRE fails to open when installed for the first time or if any changes are made to the IIS server. It fails with snap-in error and when you try to open the snap-in page, the following content is displayed:

This collection already contains an address with scheme http.  There can be at most one address per scheme in this collection. If your service is being hosted in IIS you can fix the problem by setting 'system.serviceModel/serviceHostingEnvironment/multipleSiteBindingsEnabled' to true or specifying 'system.serviceModel/serviceHostingEnvironment/baseAddressPrefixFilters'."

Cause: This error occurs because http port number 443 is already in use by another application and the IIS server is not configured to handle multiple binding to the same port.

Solution: Configure IIS server to handle multiple port bindings. Contact the vendor (Microsoft) to configure it.

Since these services were offered from an IIS Web Server, checking the Bindings on the Root Site fixed the problem. Someone had messed up the Site Bindings, defining rules that were overlapping themselves and messed up the services.

Fixing the correct Bindings resolved the problem, in my case, and i did not have to configure the Web.Config.

Did you see this - http://kb.discountasp.net/KB/a799/error-accessing-wcf-service-this-collection-already.aspx

You can resolve this error by changing the web.config file.

With ASP.NET 4.0, add the following lines to your web.config:

<system.serviceModel> 
     <serviceHostingEnvironment multipleSiteBindingsEnabled="true" /> 
</system.serviceModel> 

With ASP.NET 2.0/3.0/3.5, add the following lines to your web.config:

<system.serviceModel> 
     <serviceHostingEnvironment> 
          <baseAddressPrefixFilters> 
               <add prefix="http://www.YourHostedDomainName.com"/> 
          </baseAddressPrefixFilters> 
     </serviceHostingEnvironment> 
</system.serviceModel> 

In my case root cause of this issue was multiple http bindings defined at parent web site i.e. InetMgr->Sites->Mysite->properties->EditBindings. I deleted one http binding which was not required and problem got resolved.

In .Net 4, you can use the multipleSiteBindingsEnabled option:

<system.serviceModel>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true">
    </serviceHostingEnvironment>
</system.serviceModel>

Then, you won't have to specify each address.

http://msdn.microsoft.com/en-us/library/system.servicemodel.servicehostingenvironment.multiplesitebindingsenabled.aspx

And in my case it was simple: I used 'Add WCF Service' wizard in Visual Studio, which automatically created corresponding sections in app.config. Then I went on reading How to: Host a WCF Service in a Managed Application. The problem was: I didn't need to specify the url to run the web service.

Replace:

using (ServiceHost host = new ServiceHost(typeof(HelloWorldService), baseAddress))

With:

using (ServiceHost host = new ServiceHost(typeof(HelloWorldService))

And the error is gone.

Generic idea: if you provide base address as a param and specify it in config, you get this error. Most probably, that's not the only way to get the error, thou.