Sporadic "a public action method 'subscribenewsletter' was not found" error in the log

nopCommerce 2.4 Sporadically the following error message appears in the log:

"A public action method 'SubscribeNewsletter' was not found on controller 'Nop.Web.Controllers.NewsletterController'"

Page-URL http://www.mystore.com/newsletter/subscribenewsletter
Where www.mystore.com is the actual store WEB site

Generally newsletter subscription works, no problem with it are noticed

Are there any suggestions?

Full error text follows

A public action method 'SubscribeNewsletter' was not found on controller 'Nop.Web.Controllers.NewsletterController'.
The details for the log entry.Full message:   System.Web.HttpException (0x80004005): A public action method 'SubscribeNewsletter' was not found on controller 'Nop.Web.Controllers.NewsletterController'. at System.Web.Mvc.Controller.HandleUnknownAction(String actionName) at System.Web.Mvc.Controller.ExecuteCore() at System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) at System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) at System.Web.Mvc.MvcHandler.<>c__DisplayClass6.<>c__DisplayClassb.<BeginProcessRequest>b__5() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.End() at System.Web.Mvc.MvcHandler.<>c__DisplayClasse.<EndProcessRequest>b__d() at System.Web.Mvc.SecurityUtil.<GetCallInAppTrustThunk>b__0(Action f) at System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) at System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)