Error Loading Block: Group Reg Show Details

c:\inetpub\wwwroot\Blocks\Custom\GroupRegistration.ascx.cs(591): error CS0619: 'Rock.Model.Workflow.Activate(Rock.Model.WorkflowType, string)' is obsolete: 'For improved performance, use the Activate method that takes a WorkflowTypeCache parameter instead. IMPORTANT NOTE: When using the new method, the Workflow object that is returned by that method will not have the WorkflowType property set. If you are referencing the WorkflowType property on a Workflow returned by that method, you will get a Null Reference Exception! You should use the new WorkflowTypeCache property on the workflow instead.'

   at System.Web.Compilation.BuildManager.PostProcessFoundBuildResult(BuildResult result, Boolean keyFromVPP, VirtualPath virtualPath)
   at System.Web.Compilation.BuildManager.GetBuildResultFromCacheInternal(String cacheKey, Boolean keyFromVPP, VirtualPath virtualPath, Int64 hashCode, Boolean ensureIsUpToDate)
   at System.Web.Compilation.BuildManager.GetVPathBuildResultFromCacheInternal(VirtualPath virtualPath, Boolean ensureIsUpToDate)
   at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate)
   at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate)
   at System.Web.UI.TemplateControl.LoadControl(VirtualPath virtualPath)
   at Rock.Web.UI.RockPage.OnInit(EventArgs e)