Recurring page error

hi,
i open the dashboard but the page recurring show this error:
Reference to an object not set on an object instance.

[NullReferenceException: Riferimento a un oggetto non impostato su un’istanza di oggetto.]
Hangfire.Dashboard.Pages.RecurringJobsPage.Execute() +3844
Hangfire.Dashboard.RazorPage.TransformText(String body) +26
Hangfire.Dashboard.RazorPage.ToString() +7
Hangfire.Dashboard.RazorPageDispatcher.Dispatch(DashboardContext context) +65
Hangfire.Dashboard.<>c__DisplayClass1_2.b__1(IDictionary`2 env) +341
Microsoft.Owin.Mapping.d__0.MoveNext() +274
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.d__5.MoveNext() +182
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.Owin.Security.Infrastructure.d__0.MoveNext() +638
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.Owin.Security.Infrastructure.d__0.MoveNext() +638
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.Owin.Security.Infrastructure.d__0.MoveNext() +638
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.Owin.Security.Infrastructure.d__0.MoveNext() +638
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.Owin.Security.Infrastructure.d__0.MoveNext() +638
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.Owin.Security.Infrastructure.d__0.MoveNext() +638
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.Owin.Security.Infrastructure.d__0.MoveNext() +638
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.AspNet.Identity.Owin.d__0.MoveNext() +404
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.AspNet.Identity.Owin.d__0.MoveNext() +404
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.AspNet.Identity.Owin.d__0.MoveNext() +404
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.AspNet.Identity.Owin.d__0.MoveNext() +404
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.d__5.MoveNext() +182
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +61
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.d__2.MoveNext() +180
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.StageAsyncResult.End(IAsyncResult ar) +69
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar) +64
System.Web.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +380
System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +48
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +159

any help?

br
Max