When I start my app on iPhone with a synchronized mac with visual studio 2019, I get the error : 

```
error: * Assertion at ../../../../../mono/metadata/class-init.c:4109, condition `klass' not met

```

I assume it is related to my page because it crashes at the `MainPage = new myPage();` in App.cs.

I can add the whole error print if required.

Any help ?

**Edit : a few more informations about the code :**

The page's constructor does the following :

* `InitializeComponent();`
* A database call using `WebRequest`, `StreamWriter`, `WebResponse`
* Uses `JObject` to parse the anwser and update some Label
* Add `Grid` to my `Layout` : The `Grid` is using :
 `AbsoluteLayout`, `StackLayout`, `Frame`, `TapGestureRecognizer`, `Image`, `Button`, `Label`

The xaml : 

```
 <ContentPage.Content>   
        <StackLayout x:Name="stackMainWrapper"
                     BackgroundColor="White">
            <StackLayout x:Name="stackPageHeader"
                         Padding="20,10,20,0" >
                <StackLayout x:Name="stackHeaderNavigation"
                             Orientation="Horizontal">
                    <myApp:SvgIcon x:Name="svgBtnUser" 
                                         ResourceId="myApp.assets.icons.svg.menu.svg" 
                                         WidthRequest="25"
                                         Margin="0,0,10,0"
                                         VerticalOptions="Center">
                        <myApp:SvgIcon.GestureRecognizers>
                            <TapGestureRecognizer Tapped="GoToMenu" />
                        </myApp:SvgIcon.GestureRecognizers>
                    </myApp:SvgIcon>
                    <Label x:Name="labelPageName" 
                               Text=""
                               Style="{StaticResource TitleLabelStyle}"
                               VerticalOptions="Center" />
                    <Button x:Name="btncreate"
                            Text=""
                            Style="{StaticResource ButtonRegularBlue}"
                            Margin="0,10"
                            Clicked=""
                            HorizontalOptions="EndAndExpand"/>
                    <myApp:SvgIcon x:Name="svgBtnFilterResults" 
                                         ResourceId="myApp.assets.icons.svg.search.svg" 
                                         WidthRequest="25"
                                         Margin="10,0,0,0"
                                         CornerRadius="50"
                                         Padding="10,0"
                                         IsVisible="False"
                                         BackgroundColor="{StaticResource LightGreyStyled}"
                                         HorizontalOptions="End"
                                         VerticalOptions="Center">
                        <myApp:SvgIcon.GestureRecognizers>
                            <TapGestureRecognizer
Tapped="BtnFilterResults_Clicked" />
                        </myApp:SvgIcon.GestureRecognizers>
                    </myApp:SvgIcon>
                </StackLayout>

            </StackLayout>
            <controls:ShadowLine />

            <ScrollView x:Name="scrollPageBody"
                        Margin="0">
                <StackLayout x:Name="PageBody"
                         Padding="20" >
                    <Label x:Name="" 
                       Text=""
                       Style="{StaticResource RegularLabelStyle}"
                       HorizontalTextAlignment="Center"
                       Margin="0,0,0,20"/>
                </StackLayout>
            </ScrollView>
        </StackLayout>
    </ContentPage.Content>
</ContentPage>

```

**Edit : Adding the exception trace :**

> 
> 2019-06-13 11:25:52.743 myapp.iOS[682:181626] error: \* Assertion at
>  ../../../../../mono/metadata/class-init.c:4109, condition `klass' not
>  met
> 
> 
> ================================================================= Native Crash Reporting
>  ================================================================= Got a SIGABRT while executing native code. This usually indicates a fatal
>  error in the mono runtime or one of the native libraries used by your
> 
> 
> application.
> ============
> 
> 
> ================================================================= Basic Fault Adddress Reporting
>  ================================================================= Memory around native instruction pointer (0x1d3bb20dc):0x1d3bb20cc fd
>  7b c1 a8 c0 03 5f d6 10 29 80 d2 01 10 00 d4 .{....\_..)......
> 
> 
> 0x1d3bb20dc c3 00 00 54 fd 7b bf a9 fd 03 00 91 55 d6 ff 97 
>  ...T.{......U...
> 
> 
> 0x1d3bb20ec bf 03 00 91 fd 7b c1 a8 c0 03 5f d6 90 29 80 d2 
>  .....{.. ..\_..).. 0x1d3bb20fc 01 10 00 d4 c3 00 00 54 fd 7b bf a9 fd
>  03 00 91 .......T.{.... ..
> 
> 
> ================================================================= Native stacktrace:
>  ================================================================= 0x1005752fc -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : (null) 0x10056bc1c -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : (null) 0x1d3c259ec - /usr/lib/system/libsystem\_platform.dylib :
>  0x1d3c2b094 - /usr/lib/system/libsystem\_pthread.dylib :
>  0x1d3b0bea8 - /usr/lib/system/libsystem\_c.dylib : abort
>  0x1006f1c7c -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_find\_protocol\_wrapper\_type 0x1006d2018 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : mono\_pmip 0x1006d20a4 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : mono\_pmip 0x1005adc78 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : mono\_pmip 0x100713638 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_ L'exécution de l'application est terminée.
>  localized\_string\_format\_9 0x100710edc -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x100702b78 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x100706ad8 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x100706ad8 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x100703a80 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x100701e50 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x10057c294 -
>  /var/containers/Bundle/Applic
>  ation/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS :
>  mono\_pmip 0x10061794c -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : mono\_pmip 0x10061af84 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : mono\_pmip 0x10047904c -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : (null) 0x100479844 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : (null) 0x2007d0594 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  Échec de l'arrêt de l'application : An error occurred on
>  client IDB1610517 while executing a reply for topic
>  xvs/idb/16.1.0.517/stop-app 0x2007d5d20 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x2000992dc -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  L'exécution de l'application est terminée. 0x2000a1874 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x200098f60 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x200099850 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x200097b9c -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x200097864 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x20009c3a4 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x20009d188 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  \_performActionsWithDelayForTransitionContext 0x20009c25c - /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x2007cee30 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x2000a0f5c -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x2007d4328 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x2003d0ba8 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  0x1d69909fc -
>  /System/Library/PrivateFrameworks/FrontBoardServices.framework/FrontBoardServices
>  : 0x1d699a40c -
>  /System/Library/PrivateFrameworks/FrontBoardServices.framework/FrontBoardServices
>  : 0x1d6999c14 -
>  /System/Library/PrivateFrameworks/FrontBoardServices.framework/FrontBoardServices
>  : 0x1d3a557d4 - /usr/lib/system/libdispatch.dylib :
>  0x1d39fa5d8 - /usr/lib/system/libdispatch.dylib :
>  0x1d69cb040 -
>  /System/Library/PrivateFrameworks/FrontBoardServices.framework/FrontBoardServices
>  : 0x1d69cacdc -
>  /System/Library/PrivateFrameworks/FrontBoardServices.framework/FrontBoardServices
>  : 0x1d69cb294 -
>  /System/Library/PrivateFrameworks/FrontBoardServices.framework/FrontBoardServices
>  : 0x1d3fa7018 -
>  /System/Library/Frameworks/CoreFoundation.framework/CoreFoundation :
>  0x1d3fa6f98 -
>  /System/Library/Frameworks/CoreFoundation.framework/CoreFoundation :
>  0x1d3fa6880 -
>  /System/Library/Frameworks/CoreFoundation.framework/CoreFoundation :
>  0x1d3fa17bc -
>  /System/Library/Frameworks/CoreFoundation.framework/CoreFoundation :
>  0x1d3fa10b0 -
>  /System/Library/Frameworks/CoreFoundation.framework/CoreFoundation :
>  CFRunLoopRunSpecific 0x1d61a179c -
>  /System/Library/PrivateFrameworks/GraphicsServices.framework/GraphicsServices
>  : GSEventRunModal 0x2007d7978 -
>  /System/Library/PrivateFrameworks/UIKitCore.framework/UIKitCore :
>  UIApplicationMain 0x10071128c -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x10070343c -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x100703a80 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x100703a80 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x100703a80 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x100703a80 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x100701e50 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x10057c294 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : mono\_pmip 0x10061794c -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/enVisit
>  4> at <0xffffffff> at
>  UIKit.UIApplication:UIApplicationMain <0x000bc> at
>  UIKit.UIApplication:Main <0x0002a> at UIKit.UIApplication:Main
>  <0x0006a> at myapp.iOS.Application:Main <0x00016> at
>  :runtime\_invoke\_direct\_void\_string[] <0x00082>
>  ================================================================= e360.iOS.app/myapp.iOS : mono\_pmip 0x10061cf68 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : mono\_pmip 0x100560c64 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : (null) 0x100700be0 -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : xamarin\_localized\_string\_format\_9 0x10052adfc -
>  /var/containers/Bundle/Application/B332FB94-B5DA-4627-8D03-5471B0CE66FC/myapp.iOS.app/myapp.iOS
>  : (null) 0x1d3a668e0 - /usr/lib/system/libdyld.dylib : 
> 
> 
> ================================================================= Managed Stacktrace:
>  ================================================================= at <0xffffffff> at myapp.App:.ctor <0x0002c> at
>  myapp.iOS.AppDelegate:FinishedLaunching <0x0006e> at
>  :runtime\_invoke\_direct\_bool\_\_this\_\_\_UIApplication\_NSDictionary
>  <0x000b
> 
> 
>