system.serviceModel has invalid child element domainServices

Question

I get this error and really don't know how to fix it:

The element 'system.serviceModel' has invalid child element 'domainServices'. List of possible elements expected: 'behaviors, bindings, client, comContracts, commonBehaviors, diagnostics, serviceHostingEnvironment, extensions, protocolMapping, services, standardEndpoints, tracking, routing

Config:

<?xml version="1.0"?>
<configuration>
  <configSections>
    <sectionGroup name="system.serviceModel">
      <section name="domainServices" type="System.ServiceModel.DomainServices.Hosting.DomainServicesSection, System.ServiceModel.DomainServices.Hosting, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" allowDefinition="MachineToApplication" requirePermission="false" />
    </sectionGroup>
  </configSections>    
  <system.serviceModel>
    <domainServices>
      <endpoints>
        <!-- <add name="OData" type="System.ServiceModel.DomainServices.Hosting.ODataEndpointFactory, System.ServiceModel.DomainServices.Hosting.OData, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" /> -->
        <add name="soap" type="Microsoft.ServiceModel.DomainServices.Hosting.SoapXmlEndpointFactory, Microsoft.ServiceModel.DomainServices.Hosting, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
        <!-- <add name="JSON" type="Microsoft.ServiceModel.DomainServices.Hosting.JsonEndpointFactory, Microsoft.ServiceModel.DomainServices.Hosting, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" /> -->
      </endpoints>
    </domainServices>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" />
    <behaviors>
      <serviceBehaviors>
        <behavior name="">
          <serviceThrottling  maxConcurrentCalls="100"  maxConcurrentSessions="100"  maxConcurrentInstances="10"  />
          <serviceMetadata httpGetEnabled="true" />
          <serviceDebug includeExceptionDetailInFaults="false" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>
 </configuration>

Answer 1

Sometimes this sort of error ("system.ServiceModel has an invalid child element XXXX") can arise if we target an older version of .Net Framework than what is expected. This can be resolved by opening the Project Properties and then modifying the Target framework from the Application tab. Hope this is useful to someone out there.