While building WCF REST service if you get below error
message:

Image 1.
Then make sure your WCF service Project's web.config
file should have below System.ServiceModel setting:
<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior>
<!-- To avoid disclosing metadata
information, set the values below to false before deployment -->
<serviceMetadata httpGetEnabled="true" httpsGetEnabled="true" />
<!-- To receive exception details
in faults for debugging purposes,
set the value below to true. Set to false before deployment to avoid
disclosing exception information -->
<serviceDebug includeExceptionDetailInFaults="false" />
</behavior>
</serviceBehaviors>
<endpointBehaviors>
<behavior>
<webHttp helpEnabled="True"/>
</behavior>
</endpointBehaviors>
</behaviors>
<protocolMapping>
<add binding="webHttpBinding" scheme="http" />
</protocolMapping>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" />
<standardEndpoints>
<webScriptEndpoint>
<standardEndpoint name="" crossDomainScriptAccessEnabled="true" />
</webScriptEndpoint>
</standardEndpoints>
</system.serviceModel>
Now run your WCF REST
service:

Image 2.