Error: Specified cast is not valid. Xaml - xamarin

Question

I have a xaml, which has a grid with listview and button, and at the
moment of compiling this error appears:
Error: Specified cast is not valid.
I think the problem may be in the listview that is inside the grid, but I have not really been able to find a solution
this is my xaml:
<?xml version="1.0" encoding="utf-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="FCR.App.Views.AdvanceSearchResultPage" Title="AdvanceSearchResultPage" xmlns:extended="clr-namespace:FCR.App.ExtendedClasses;assembly=FCR.App">
<ContentPage.Padding>
<OnPlatform x:TypeArguments="Thickness" iOS="0, 10, 0, 0" WinPhone="20,20,20,20" />
</ContentPage.Padding>
<ContentPage.Content>
<StackLayout VerticalOptions="StartAndExpand">
<ContentView IsVisible="false" x:Name="TitleHC">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="0.5*" />
<ColumnDefinition Width="9.5*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Image Source="blue_circle.png" Grid.Column="0" />
<StackLayout Padding="0,4,0,5" VerticalOptions="Fill" Grid.Column="1">
<Label VerticalOptions="CenterAndExpand" TextColor="#0368b1" Text="Histórico de conéxiones" FontSize="20">
<Label.FontFamily>
<OnPlatform x:TypeArguments="x:String">
<OnPlatform.iOS>FrutigerLTStd-Cn</OnPlatform.iOS>
<OnPlatform.Android>FrutigerLTStd-Cn.otf#FrutigerLTStd-Cn</OnPlatform.Android>
</OnPlatform>
</Label.FontFamily>
</Label>
</StackLayout>
</Grid>
</ContentView>
<ContentView IsVisible="false" x:Name="TitleHM">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="0.5*" />
<ColumnDefinition Width="9.5*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Image Source="blue_circle.png" Grid.Column="0" />
<StackLayout Padding="0,4,0,5" VerticalOptions="Fill" Grid.Column="1">
<Label VerticalOptions="CenterAndExpand" TextColor="#0368b1" Text="Histórico de módificaciones" FontSize="20">
<Label.FontFamily>
<OnPlatform x:TypeArguments="x:String">
<OnPlatform.iOS>FrutigerLTStd-Cn</OnPlatform.iOS>
<OnPlatform.Android>FrutigerLTStd-Cn.otf#FrutigerLTStd-Cn</OnPlatform.Android>
</OnPlatform>
</Label.FontFamily>
</Label>
</StackLayout>
</Grid>
</ContentView>
<Grid VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<ContentView x:Name="contentListView" IsVisible="true" Padding="0,10,0,0" BackgroundColor="White" Grid.Row="0">
<ListView x:Name="resultListView" BackgroundColor="White" HasUnevenRows="true" HorizontalOptions="FillAndExpand" SeparatorVisibility="None">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<StackLayout BackgroundColor="White" Padding="0" Opacity="90">
<ContentView Padding="1,0,1,1" BackgroundColor="Gray">
<Grid
BackgroundColor="White">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="0.7*">
</ColumnDefinition>
<ColumnDefinition Width="0.15*">
</ColumnDefinition>
<ColumnDefinition Width="0.15*">
</ColumnDefinition>
</Grid.ColumnDefinitions>
<StackLayout Grid.Column="0">
<Label Margin="-5" Text="{Binding NombreCompleto}" TextColor="Gray" Font="Bold,13" />
<Label Margin="-5"
Text="{Binding OrganizacionMayusculas}" TextColor="Gray" FontSize="13" />
<Label Margin="-5" Text="{Binding Region}" TextColor="Gray" FontSize="13" />
</StackLayout>
<Label Margin="0,0,0,2" Text="Detalle" Grid.Column="1"
Font="Bold, 13" ClassId="{Binding IdContacto}" TextColor="Gray" VerticalOptions="End">
<Label.FontFamily>
<OnPlatform x:TypeArguments="x:String" iOS="8">
<OnPlatform.iOS>FrutigerLTStd-BoldCn</OnPlatform.iOS>
<OnPlatform.Android>FrutigerLTStd-BoldCn.otf#FrutigerLTStd-BoldCn</OnPlatform.Android>
</OnPlatform>
</Label.FontFamily>
<Label.GestureRecognizers>
<TapGestureRecognizer Tapped="OnTapGestureRecognizerDetail" />
</Label.GestureRecognizers>
</Label>
<Label Margin="0,0,0,2" Text="Borrar" Grid.Column="2"
Font="Bold, 13" ClassId="{Binding IdContacto}" TextColor="Gray" VerticalOptions="End">
<Label.FontFamily>
<OnPlatform x:TypeArguments="x:String" iOS="8">
<OnPlatform.iOS>FrutigerLTStd-BoldCn</OnPlatform.iOS>
<OnPlatform.Android>FrutigerLTStd-BoldCn.otf#FrutigerLTStd-BoldCn</OnPlatform.Android>
</OnPlatform>
</Label.FontFamily>
<Label.GestureRecognizers>
<TapGestureRecognizer Tapped="OnTapGestureRecognizerDelete" />
</Label.GestureRecognizers>
</Label>
</Grid>
</ContentView>
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</ContentView>
<StackLayout>
<extended:CustomButton Text="Volver" Grid.Row="1" x:Name="dismissbutton" Clicked="OnDismissButtonClicked" WidthRequest="100" Style="{StaticResource buttonStyle}" />
</StackLayout>
</Grid>
</StackLayout>
</ContentPage.Content>
</ContentPage>

Answer 1

The problem
Generally these sort of error you might find while working with data binding. While we are trying to bind a different type with some controls which the complier is not exactly expecting.
There are few places I could find the binding little odd -
ClassId="{Binding IdContacto}"
I am not sure whether you are binding correctly or not. If I were you I would have removed all the ClassId bindings and then go ahead with build compiling the process.
Also I would try to comment out the OnPlatform code and build/compile/Run the project.
These are some long shots which you may try. After looking at the whole Stacktrace may be we will be able to diagnose more towards the exact issue.