Is there any example how to call AddListMembersList? I tried with: but I get error: “error”:{ “code”:””,”message”:”Request message has unresolved parameters.”,”innererror”:{ “message”:”Request message has unresolved parameters.”,”type”:”Microsoft.Crm.CrmHttpException”,”stacktrace”:” bei Microsoft.Crm.Extensibility.OData.CrmODataRoutingConvention.SelectAction(ODataPath odataPath, HttpControllerContext controllerContext, ILookup`2 actionMap)rn bei System.Web.OData.Routing.ODataActionSelector.SelectAction(HttpControllerContext controllerContext)rn bei System.Web.Http.ApiController.ExecuteAsync(HttpControllerContext controllerContext, CancellationToken cancellationToken)rn bei System.Web.Http.Dispatcher.HttpControllerDispatcher.d__1.MoveNext()” Any advice? Answer Exact answer can be found here: http://butenko.pro/2018/03/01/how-to-add-records-to-marketing-list-using-webapi/ From link adjusted to my example: