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POCombobox SelectedValue "Cannot save value from target back to source"
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  1. POCombobox SelectedValue "Cannot save value from target back to source"
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    copied!<p>I have the following combobox:</p> <pre><code>&lt;Controls:RadComboBox ItemsSource="{Binding UsuariosApp,Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" SelectedValue="{Binding SelectedUsuario}" IsEnabled="{Binding ChangeUserEnabled}"/&gt; </code></pre> <p>Viewmodel:</p> <pre><code>public List&lt;UsuarioDetalle&gt; UsuariosApp { get { if (_users == null) { _users = new List&lt;UsuarioDetalle&gt;(); if (AuthenticationController.ChildUserEntities != null) _users.AddRange(AuthenticationController.ChildUserEntities); } return _users; } set { _users = value; OnPropertyChanged(() =&gt; UsuariosApp); } } public object SelectedUsuario { get { if (UsuariosApp != null &amp;&amp; UsuariosApp.Count &gt; 0) { AuthenticationController.CurrentUser = UsuariosApp[0].idUsuario; AuthenticationController.CurrentUserRole = (RolesUsuario)UsuariosApp[0].idStTipoUsuario; _lastUser = UsuariosApp[0]; return UsuariosApp[0]; } return null; } set { if (!((UsuarioDetalle)_lastUser).idUsuario.ToString().Equals(((UsuarioDetalle)value).idUsuario.ToString())) { bool? confirmation = SwitchUserConfirmation(); if (confirmation.HasValue &amp;&amp; confirmation.Value.Equals(false)) { // Alex: cancelar el cambio de valor del combo ChangeUser = _lastUser; } else { ResetWorkspace(value); } } else { ResetWorkspace(value); } } } </code></pre> <p>It works but in the output I have the following error when I change the value of the combobox</p> <blockquote> <p>System.Windows.Data Error: 8 : Cannot save value from target back to source. BindingExpression:Path=SelectedUsuario; DataItem='MainWindowViewModel' (HashCode=26603182); target element is 'RadComboBox' (Name='comboChildUsers'); target property is 'SelectedValue' (type 'Object') TargetInvocationException:'System.Reflection.TargetInvocationException: Se produjo una excepción en el destino de la invocación. ---> System.NullReferenceException: Referencia a objeto no establecida como instancia de un objeto.</p> </blockquote> <p>What could be the reason?</p>
 

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