# Object reference was null

**URL:** https://forums.fusetools.com/t/object-reference-was-null/5747
**Category:** Bug Reports
**Created:** [July 5, 2017, 8:10pm UTC](https://forums.fusetools.com/t/object-reference-was-null/5747 "2017-07-05T20:10:07Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![Cristian\_Karmy](https://yyz1.discourse-cdn.com/flex035/user_avatar/forums.fusetools.com/cristian_karmy/32/480_2.png) [@Cristian\_Karmy](https://forums.fusetools.com/u/Cristian_Karmy)
#### Post date: [July 5, 2017, 8:10pm UTC](https://forums.fusetools.com/t/object-reference-was-null/5747/1 "2017-07-05T20:10:07Z")

</div>

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!

```auto
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)

```

---

<div class="post-metadata">

### Author: ![Uldis](https://yyz1.discourse-cdn.com/flex035/user_avatar/forums.fusetools.com/uldis/32/657_2.png) [@Uldis](https://forums.fusetools.com/u/Uldis)
#### Post date: [July 5, 2017, 10:34pm UTC](https://forums.fusetools.com/t/object-reference-was-null/5747/2 "2017-07-05T22:34:40Z")

</div>

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.