Question

In Following code I’m getting error as:

Cannot create an instance of “MainViewModels” … also, always DataContext is marked
with red lines. Any help is appreciated.

<Window x:Class="SimpleMvvmUsingWPF.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:SimpleMvvmUsingWPF"
        Title="MainWindow" Height="350" Width="525"
        >

    <Window.Resources>
        <local:MainViewModels x:Key="MainViewModels" />
    </Window.Resources>


    <Grid DataContext="{StaticResource MainViewModel}" >
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto"/>
            <ColumnDefinition Width="Auto"/>
        </Grid.ColumnDefinitions>

        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <StackPanel Orientation="Horizontal">
            <TextBlock Text="First Name:" Margin="5"></TextBlock>
            <TextBox Grid.Column="1" Margin="5" Width="100" Text="{Binding ModelPerson.FirstName, Mode=TwoWay, ValidatesOnDataErrors=True}"></TextBox>
        </StackPanel>
        <StackPanel Orientation="Horizontal" Grid.Row="1">
            <TextBlock  Text="Last Name:" Margin="5"></TextBlock>
            <TextBox Grid.Column="1" Margin="5" Width="100" Text="{Binding ModelPerson.LastName}"></TextBox>
        </StackPanel>
        <StackPanel Orientation="Horizontal" Grid.Row="2">
            <TextBlock  Text="Update Date:" Margin="5"></TextBlock>
            <TextBox Grid.Column="1" Margin="5" Width="100" Text="{Binding ModelPerson.UpdatedDate}"></TextBox>
        </StackPanel>
        <Button  Grid.Column="2" Grid.Row="3" Width="100"/>

    </Grid>


</Window>

Answer 1

The problem was due to using wrong argument in INotifyPropertyChanged interface implementation. I was passing a wrong argument to OnPropertyChanged() method.