Migration from new Xamarin project to .NET MAUI.Android failed to load assembly/dll

Question

Migration from new Xamarin project to .NET MAUI.Android failed to load assembly/dll

Wheelstring 190

Hallo all

I create new project Mobile App (Xamarin.Forms) + link and USE my own dll (signed netstandard2.0 dll)

Run OK in Android emulator

I migrate this new project with tool "upgrade-assistant upgrade" to .NET 7 MAUI (all 3 project Base/Android/IOS) (dll are linked /Solution Explorer OK/ but NOT USED)

changed in MainActivity.cs/OnCreate> Xamarin.Essentials.Platform.Init(this, savedInstanceState); to Microsoft.Maui.ApplicationModel.Platform.Init(this, savedInstanceState);

Run OK in Android emulator

now in AboutPage.cs'constructor I use my function from dll:

InitializeComponent();

LabelName.Text = MyNamespace.MyClassName.MySpecEnum.MySpecEnumValue.ToString();

Build OK, but exception in Android emulator while app runnning:

System.Reflection.TargetInvocationException: 'Exception has been thrown by the target of an invocation.'

[monodroid-assembly] open_from_bundles: failed to load assembly MydllName.dll

Maybe/probably this error is connected with error:

Error XAGJS7028 System.IO.FileNotFoundException: Could not load assembly MydllName.dll, Perhaps it doesn't exist in the Mono for Android profile?¨

What should I do for using my dll? Thanks in advance!

It is completly a new project see screen

Shanghai

I am stuck :-(, Any help is appreciated.

Anonymous

2024-03-05T08:21:29.57+00:00

Firstly, please find your project folder and delete bin and obj folders, then rebuild your project and uninstall this application in your Android devices or emulators. In the end, you can debug it. If you will get the same issue.
Wheelstring 190 Reputation points

2024-03-05T09:56:42.17+00:00

Hi

thanks for answer, but I don't have to clean cause this is completly a new project see screen

I am stuck :-(, Any help is appreciated.
Anonymous

2024-03-07T02:38:15.32+00:00

Firstly, please try to migrate Xamarin to MAUI .NET 8 version. Here are some fixes in .NET 8.

If you still get this issue. check with build properties of this DLL to make sure assembly is getting copied to final output bundle.

You can create a new MAUI project and add your DLL in it. Will you get the same issue?
Wheelstring 190 Reputation points

2024-03-08T16:55:00.63+00:00

Hi Leon

Thanks a lot for answer! You are right, migration to the .NET 7 is buggy...

when I migrate a new teplate project to .NET 8 is all OK (including dll)

But I migrate quite complex project (with webview...) from Xamarin to Maui .NET8

I have no compile error, dll looks OK, but application fall in Android emulator, no error in output tab, call stack tab is empty...

I am tired therefrom, maybe I stay in Xamarin.Forms (but there is WCF unreliable...)

thanks and nice weekend

W
Anonymous

2024-03-12T06:04:53.5066667+00:00

but application fall in Android emulator, no error in output tab, call stack tab is empty...

Did you test it in the release mode or debug mode?
Wheelstring 190 Reputation points

2024-03-12T07:35:41.27+00:00

Hi Leon

Yes I did (F5 debug)

I think problem was <WebView>, I filled content page directly (no URL) via <WebView.Source><HtmlWebViewSource><HtmlWebViewSource.Html>[CDATA[ as described on here: https://learn.microsoft.com/cs-cz/dotnet/maui/user-interface/controls/webview?view=net-maui-8.0&pivots=devices-android

I tried simple project with webview/HtmlWebViewSource no working...

regards Wheelstring

Anonymous

Please set WidthRequest and HeightRequest for your webview like following code. Is that working?

<WebView        
         WidthRequest="500"
         HeightRequest="500">
    <WebView.Source>
        <HtmlWebViewSource>
            <HtmlWebViewSource.Html>

               <![CDATA[
    <HTML>
    <BODY>
    <H1>as described on here: https://learn.microsoft.com/cs-cz/dotnet/maui/user-interface/controls/webview?view=net-maui-8.0&pivots=devices-android</H1>
    <P>Welcome to WebView.</P>
    </BODY>
    </HTML>
    ]]>      

            </HtmlWebViewSource.Html>
        </HtmlWebViewSource>
    </WebView.Source>
</WebView>

Wheelstring 190 Reputation points

2024-03-13T10:27:54.11+00:00
Hi Leon

you are a clever man! thanks!

Of course I had WidthRequest and HeightRequest but was too high = 5000 (see code of old Xamarin framework project) it was reason why I didn't see the content... Now in "temp project" all right see picture. thanks a lot for help!

I have a last question:

The reason why I had WidthRequest and HeightRequest = 5000 (too high) was FULL SCREEN of webview on any device. And it work well in Xamarin framework...

Do you know the best approach how to set MAUI (mayby WidthRequest and HeightRequest or) for FULL SCREEN of webview on any device? (cause I don't know final resolution of client's mobile = I can't set direct for example: WidthRequest = 360 and HeightRequest = 800) (Set something in StackLayout? ..I have a <AbsoluteLayout> content...)

Thanks!

WheelString

<local:HybridWebView Grid.Row="0" Grid.Column="0" x:Name="hybridWebView" VerticalOptions="EndAndExpand" WidthRequest="5000" HeightRequest="5000"> <WebView.Source> <HtmlWebViewSource> <HtmlWebViewSource.Html x:Uid="HtmlSource"> <![CDATA[ <!DOCTYPE html> <html> <head> <title>TITLE</title> </head> <body style=""> </body> </html> ]]> </HtmlWebViewSource.Html> </HtmlWebViewSource> </WebView.Source> </local:HybridWebView>

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Anonymous

2024-03-05T08:21:29.57+00:00

Firstly, please find your project folder and delete bin and obj folders, then rebuild your project and uninstall this application in your Android devices or emulators. In the end, you can debug it. If you will get the same issue.
Wheelstring 190 Reputation points

2024-03-05T09:56:42.17+00:00

Hi

thanks for answer, but I don't have to clean cause this is completly a new project see screen

I am stuck :-(, Any help is appreciated.
Anonymous

2024-03-07T02:38:15.32+00:00

Firstly, please try to migrate Xamarin to MAUI .NET 8 version. Here are some fixes in .NET 8.

If you still get this issue. check with build properties of this DLL to make sure assembly is getting copied to final output bundle.

You can create a new MAUI project and add your DLL in it. Will you get the same issue?
Wheelstring 190 Reputation points

2024-03-08T16:55:00.63+00:00

Hi Leon

Thanks a lot for answer! You are right, migration to the .NET 7 is buggy...

when I migrate a new teplate project to .NET 8 is all OK (including dll)

But I migrate quite complex project (with webview...) from Xamarin to Maui .NET8

I have no compile error, dll looks OK, but application fall in Android emulator, no error in output tab, call stack tab is empty...

I am tired therefrom, maybe I stay in Xamarin.Forms (but there is WCF unreliable...)

thanks and nice weekend

W
Anonymous

2024-03-12T06:04:53.5066667+00:00

but application fall in Android emulator, no error in output tab, call stack tab is empty...

Did you test it in the release mode or debug mode?
Wheelstring 190 Reputation points

2024-03-12T07:35:41.27+00:00

Hi Leon

Yes I did (F5 debug)

I think problem was <WebView>, I filled content page directly (no URL) via <WebView.Source><HtmlWebViewSource><HtmlWebViewSource.Html>[CDATA[ as described on here: https://learn.microsoft.com/cs-cz/dotnet/maui/user-interface/controls/webview?view=net-maui-8.0&pivots=devices-android

I tried simple project with webview/HtmlWebViewSource no working...

regards Wheelstring
Anonymous

2024-03-13T02:24:28.3233333+00:00

Please set WidthRequest and HeightRequest for your webview like following code. Is that working?

<WebView WidthRequest="500" HeightRequest="500"> <WebView.Source> <HtmlWebViewSource> <HtmlWebViewSource.Html> <![CDATA[ <HTML> <BODY> <H1>as described on here: https://learn.microsoft.com/cs-cz/dotnet/maui/user-interface/controls/webview?view=net-maui-8.0&pivots=devices-android</H1> <P>Welcome to WebView.</P> </BODY> </HTML> ]]> </HtmlWebViewSource.Html> </HtmlWebViewSource> </WebView.Source> </WebView>
Wheelstring 190 Reputation points

2024-03-13T10:27:54.11+00:00

Hi Leon

you are a clever man! thanks!

Of course I had WidthRequest and HeightRequest but was too high = 5000 (see code of old Xamarin framework project) it was reason why I didn't see the content... Now in "temp project" all right see picture. thanks a lot for help!

I have a last question:

The reason why I had WidthRequest and HeightRequest = 5000 (too high) was FULL SCREEN of webview on any device. And it work well in Xamarin framework...

Do you know the best approach how to set MAUI (mayby WidthRequest and HeightRequest or) for FULL SCREEN of webview on any device? (cause I don't know final resolution of client's mobile = I can't set direct for example: WidthRequest = 360 and HeightRequest = 800) (Set something in StackLayout? ..I have a <AbsoluteLayout> content...)

Thanks!

WheelString

<local:HybridWebView Grid.Row="0" Grid.Column="0" x:Name="hybridWebView" VerticalOptions="EndAndExpand" WidthRequest="5000" HeightRequest="5000"> <WebView.Source> <HtmlWebViewSource> <HtmlWebViewSource.Html x:Uid="HtmlSource"> <![CDATA[ <!DOCTYPE html> <html> <head> <title>TITLE</title> </head> <body style=""> </body> </html> ]]> </HtmlWebViewSource.Html> </HtmlWebViewSource> </WebView.Source> </local:HybridWebView>

Answer 1

Hello,

Do you know the best approach how to set MAUI (mayby WidthRequest and HeightRequest or) for FULL SCREEN of webview on any device?

You can add x:name for webview.

<WebView   
     BackgroundColor="Gray"
     x:Name="myWebview"
     
>

Then you can get the screen's width and height in the background code, After it, you can set it to the Webview.

protected override void OnAppearing()
{
     base.OnAppearing();
    myWebview.WidthRequest=DeviceDisplay.MainDisplayInfo.Width;
     myWebview.HeightRequest=DeviceDisplay.MainDisplayInfo.Height;   

}

By the way, please keep one thread for one question, it will help others have similar issue to find answer quickly.

Best Regards,

Leon Lu

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Wheelstring 190 Reputation points

2024-03-14T10:15:14.77+00:00

Hi Leon

Many thaaaaaaaanks for help!

and you are absoluttely right (one thread for one question) I'm going to get better ;-)

W

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Migration from new Xamarin project to .NET MAUI.Android failed to load assembly/dll

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