Error when configuring feed

I'm using the Feed manager on my Nopcommerce 3.50 site.  When I edit a feed, I get the message "Error Happened".  On the product filter page the product categories are not displayed and I get the following message in the log.  Any ideas on what is causing this or how I can resolve this?  


System.MissingMethodException: Method not found: 'System.Collections.Generic.IList`1<Nop.Core.Domain.Catalog.Category> Nop.Services.Catalog.ICategoryService.GetAllCategoriesByParentCategoryId(Int32, Boolean)'. at FoxNetSoft.Plugin.Feed.Manager.Controllers.FeedsController.CategoryFilterList(DataSourceRequest command, Int32 feedId, Int32 categoryId) at lambda_method(Closure , ControllerBase , Object[] ) at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End() at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End() at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass21.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End() at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) at System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End() at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) at System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResul

I don't know, but this method is in standart NopCommerce kernel libraries.

1. Download the new version of plugin from our site (download from the product page).
[url=www.foxnetsoft.com/content/files/foxnetsoft.feedmanager.zip]www.foxnetsoft.com/content/files/foxnetsoft.feedmanager.zip[/url]

2. Replace plugin folder (all files), you needn't uninstall and install plugin.
3. Open the Global.asax in site root folder and add spacebar to the end of the file. After it IIS recreates internal cache.
4. Try it.
5. Write me about result.