Object reference was null

Bug Reports
1

In my project I get several times this error and the only way to work again the app is to click many times in Try Again button!

Uno.NullReferenceException: Object reference was null
   at Fuse.Reactive.ExpressionBinding.OnUnrooted()
   at Fuse.Reactive.DataBinding.OnUnrooted()
   at Fuse.Binding.Unroot()
   at Fuse.Node.UnrootBindings()
   at Fuse.Node.OnUnrooted()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.TextControl.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.ScrollViewBase.OnUnrooted()
   at Fuse.Controls.ScrollView.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Node.Unrelate(Fuse.Visual,Fuse.Node)
   at Fuse.Visual.OnRemoved(Fuse.Node)
   at Fuse.Visual.Uno.Collections.ICollection<Fuse.Node>.Clear()
   at Outracks.Simulator.Client.UserAppState.SetSequence`1(Uno.Collections.IList<T>,T[])
   at Outracks.Simulator.Client.UserAppState.SetIfNotEqual`1(Uno.Collections.IList<T>,T[])
   at Outracks.Simulator.Client.UserAppState.ApplyTo(Outracks.Simulator.Client.FakeApp)
   at Outracks.Simulator.Client.Reifying.OnEnterState()
   at Outracks.Simulator.Client.Application.SetState(Outracks.Simulator.Client.State)
   at Outracks.Simulator.Client.Application.OnUpdate()
   at Fuse.App.OnTick(object,Uno.Platform.TimerEventArgs)
   at Uno.Platform.Display.OnTick(Uno.Platform.TimerEventArgs)
   at Uno.Platform.AndroidDisplay.OnFrameCallback(double,double)
Uno.NullReferenceException: Object reference was null
   at Fuse.Reactive.ExpressionBinding.OnUnrooted()
   at Fuse.Reactive.DataBinding.OnUnrooted()
   at Fuse.Binding.Unroot()
   at Fuse.Node.UnrootBindings()
   at Fuse.Node.OnUnrooted()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.TextControl.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.ScrollViewBase.OnUnrooted()
   at Fuse.Controls.ScrollView.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Visual.OnUnrooted()
   at Fuse.Elements.Element.OnUnrooted()
   at Fuse.Controls.Control.OnUnrooted()
   at Fuse.Controls.LayoutControl.OnUnrooted()
   at Fuse.Controls.Panel.OnUnrooted()
   at Fuse.Node.UnrootInternal()
   at Fuse.Node.Unrelate(Fuse.Visual,Fuse.Node)
   at Fuse.Visual.OnRemoved(Fuse.Node)
   at Fuse.Visual.Uno.Collections.ICollection<Fuse.Node>.Clear()
   at Outracks.Simulator.Client.UserAppState.SetSequence`1(Uno.Collections.IList<T>,T[])
   at Outracks.Simulator.Client.UserAppState.SetIfNotEqual`1(Uno.Collections.IList<T>,T[])
   at Outracks.Simulator.Client.UserAppState.ApplyTo(Outracks.Simulator.Client.FakeApp)
   at Outracks.Simulator.Client.Reifying.OnEnterState()
   at Outracks.Simulator.Client.Application.SetState(Outracks.Simulator.Client.State)
   at Outracks.Simulator.Client.Application.OnUpdate()
   at Fuse.App.OnTick(object,Uno.Platform.TimerEventArgs)
   at Uno.Platform.Display.OnTick(Uno.Platform.TimerEventArgs)
   at Uno.Platform.AndroidDisplay.OnFrameCallback(double,double)
2

Hi Cristian,

stuff like this usually happens when you’ve messed up some data bindings. It’s impossible to tell what’s the problem without seeing the code unfortunately.

If you can recall when you started getting the errors, and if you have a git commit of a change you did at that given time, that might help find the cause more easily.