how to fix 'java.lang.noclassdeffounderror' error on xamarin.android preview when use scrollview

Question

I try code below but the android preview does not work when using scroll view and ios preview work fine just does not show the images but when run the project the result in simulator and emulator is true, my problem is on the preview

this my xaml page:

<?xml version="1.0" encoding="utf-8"?>
<ContentPage Style="{StaticResource baseStyle}" xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:local="clr-namespace:Flightio" x:Class="Flightio.MainPage"
             xmlns:ffimageloadingSVG="clr-namespace:FFImageLoading.Svg.Forms;assembly=FFImageLoading.Svg.Forms"
             xmlns:fftransformations="clr-namespace:FFImageLoading.Transformations;assembly=FFImageLoading.Transformations">
   <ContentPage.Content>
        <ScrollView>
            <Grid RowSpacing="8" x:Name="grid_Main">  
                <Grid.RowDefinitions>  
                    <RowDefinition Height="45" />  
                    <RowDefinition Height="75" />  
                    <RowDefinition Height="*" /> 
                </Grid.RowDefinitions>  
                <Grid.ColumnDefinitions>  
                    <ColumnDefinition Width="*" />  
                </Grid.ColumnDefinitions>  
                <Image Source="Logo.jpg" x:Name="image_logo" HorizontalOptions="Center" Margin="0,10,0,0"/>
                <RelativeLayout HorizontalOptions="FillAndExpand" x:Name="relLay_blueMenu" BackgroundColor="#1e559e" Grid.Row="1" Margin="10,0,10,0">  
                    <ContentView BackgroundColor="White" x:Name="view_domesticMenu"
                                 Margin="0,5,0,0"
                                 RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.8}"
                                 RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.2}"
                                 RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=1}">
                                 <RelativeLayout x:Name="relLay_flightMenu" HorizontalOptions="FillAndExpand">
                                    <Label Text="aliali" TextColor="Red" XAlign="Center" Margin="10,0,10,0"/>
                                 </RelativeLayout>
                    </ContentView>
                    <ContentView BackgroundColor="#1e559e" x:Name="view_internationalFlightMenu"
                                 Margin="0,5,0,0"
                                 RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.6}"
                                 RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.2}"
                                 RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=1}"></ContentView>
                    <ContentView BackgroundColor="#1e559e" x:Name="view_hotelMenu"
                                 Margin="0,5,0,0"
                                 RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.4}"
                                 RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.2}"
                                 RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=1}"></ContentView>
                    <ContentView BackgroundColor="#1e559e" x:Name="view_trianMenu"
                                 Margin="0,5,0,0"
                                 RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.2}"
                                 RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.2}"
                                 RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=1}"></ContentView>
                    <ContentView BackgroundColor="#1e559e" x:Name="view_busMenu"
                                 Margin="0,5,0,0"
                                 RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0}"
                                 RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.2}"
                                 RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=1}">
                       <Label Text="aliali2" TextColor="Blue" XAlign="Center"/>
                    </ContentView>
                </RelativeLayout>
<!--              <ffimageloadingSVG:SvgCachedImage Source="baseline-flight.svg" x:Name="image_logo2" HorizontalOptions="Center" Grid.Row="2"/>                                    -->
             </Grid>
            </ScrollView>
     </ContentPage.Content>
</ContentPage>

and I got this error on android preview when using scroll view:

so I have two questions:

1- how to fix my android preview?

2- how show images in ios preview?

Answer 1

I had the same problem and I solved it by changing the target platform of the Android project.

From Android 9.0 (Pie) to Android 8.1 (Oreo) in the application properties and in the Android manifest.

Answer 2

1- how to fix my android preview?

I just tested you xaml code in my side and it works well in preview.

1. I use Visual Studio Community 2017, version(15.9.9)
2. you can try clean and rebuild your project.
3. try to restart your visual studio.

2- how show images in ios preview?

Try to remove the .jpg in image's name. For example:

<Image Source="Logo"/>

Also, check the tips listed here: xaml-previewer-isnt-showing-or-shows-an-error

but when run the project the result in simulator and emulator is true

I think the result in simulator and emulator is more reliable than in preview.