Xamarin Forms Migration to MAUI - Build issues

Question

Xamarin Forms Migration to MAUI - Build issues

Sreejith Sreenivasan 1,001

I have migrated my Xamarin Forms app to a MAUI using upgrade assistant. First I converted the Solution then converted the Android and iOS projects.

After that I face a lot of issues when rebuilding the project.

I have added the following to the ios project .csproj file for fixing the "doesn't have a target for 'net6.0-ios/ios-arm64'".

<PropertyGroup Condition="$(TargetFramework.Contains('-ios'))">
    <RuntimeIdentifier>ios-arm64</RuntimeIdentifier>
</PropertyGroup>

I have added the <SingleProject>true</SingleProject> property into my Android project's .csproj file under the first/main property group, closed VS, deleted Bin, Obj, .vs folders for fixing the android physical device availability issue.
Set all of the files' build action to AndroidResource in the Resource folder on the Android platform and set BundleResource in the iOS platform.
For fixing the below kind of Cannot resolve type errors, I set the Xaml build action to MauiXaml from Embedded Resource.

Error : XamlC error XFC0000 : Cannot resolve type "ContentPage". Error : XamlC error XFC0000 : Cannot resolve type "Frame". Error : XamlC error XFC0000 : Cannot resolve type "Application".

After all these fixes also I am facing some other build issues. I am adding it below:

Severity Code Description Project File Line Suppression State Error NETSDK1136 The target platform must be set to Windows (usually by including '-windows' in the TargetFramework property) when using Windows Forms or WPF, or referencing projects or packages that do so. MyProject.iOS C:\Program Files\dotnet\sdk\7.0.306\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.DefaultItems.Shared.targets 250

Severity Code Description Project File Line Suppression State Error NU1107 Version conflict detected for Xamarin.AndroidX.Browser. Install/reference Xamarin.AndroidX.Browser 1.4.0.1 directly to project MyProject to resolve this issue. MyProject -> Microsoft.Maui.Dependencies 6.0.553 -> Xamarin.AndroidX.Browser (>= 1.4.0.1) MyProject -> Xam.Plugin.HtmlLabel 5.1.0 -> Xamarin.Essentials 1.7.0 -> Xamarin.AndroidX.Browser (>= 1.3.0.5 && < 1.4.0). MyProject E:\My Projects\Xamarin\MyProject-MyProject-app\MyProject\MyProject\MyProjectMyProject.csproj 1

Severity Code Description Project File Line Suppression State Error NU1202 Package GMImagePicker.Xamarin 2.5.1 is not compatible with net6.0-ios16.1 (.NETCoreApp,Version=v6.0). Package GMImagePicker.Xamarin 2.5.1 supports: xamarinios10 (Xamarin.iOS,Version=v1.0) MyProjectMyProject.iOS E:\My Projects\Xamarin\MyProject-MyProject-app\MyProject\MyProject.iOS\MyProjectMyProject.iOS.csproj 1

Severity Code Description Project File Line Suppression State Error APT2144 invalid file path 'E:\My Projects\Xamarin\MyProject-MyProject-app\MyProject\MyProject.Android\obj\Debug\net6.0-android\res\resources\xml_\file_paths.xml'. MyProjectMyProject.Android C:\Program Files\dotnet\packs\Microsoft.Android.Sdk.Windows\32.0.485\tools\Xamarin.Android.Aapt2.targets 123

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-16T07:23:13.45+00:00
There are several issues in this thread. For further help, I have some question to confirm:

How did you migrate the Xamarin.Forms project to a MAUI project? You said you used upgrade assistant, by command line like the official doc, right? Please use .NET Upgrade Assistant Extention with VS, refer to Announcing a new version of the .NET Upgrade Assistant with support for .NET MAUI and Azure Functions! - .NET Blog . Then you could create a new MAUI project Side-by-side, and check for any errors or warnings.

You said add target in "ios project .csproj", is there a single project 's csproj file that includes TargetFrameworks element? Such as the following:

<PropertyGroup> <UseMaui>true</UseMaui> <TargetFrameworks>net7.0-android;net7.0-ios</TargetFrameworks> ...

.NET MAUI6 was no longer supported. It's recommended that you try to use .NET7. Then check if the errors still exist.

Error : XamlC error XFC0000 : Cannot resolve type "ContentPage".

This error usually means that Xamarin.Forms is also working in the MAUI project, please refer to this GitHub issue and check the Xamarin.Forms references.

Severity Code Description Project File Line Suppression State Error NETSDK1136 The target platform must be set to Windows (usually by including '-windows' in the TargetFramework property) when using Windows Forms or WPF, or referencing projects or packages that do so. MyProject.iOS C:\Program Files\dotnet\sdk\7.0.306\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.DefaultItems.Shared.targets 250

The same issue as the second point, the target platforms element should be added into the single project's csproj file but not the iOS project's.

Severity Code Description Project File Line Suppression State Error NU1107 Version conflict detected for Xamarin.AndroidX.Browser. ......

The other three errors are related to Android X. AndroidX is a part of MAUI, it's not necessary to add the Xamarin.AndroidX.Browser NuGet package. And it looks like you are still using Xamarin.Essentials whose functionality is now part of MAUI as well. Please remove the Xamarin.Essentials NuGet package from your .NET Android or .NET iOS app and migrate Xamarin.Essentials code. For more details, you can refer to Migrate Xamarin.Essentials code in .NET Android and .NET iOS apps - .NET MAUI | Microsoft Learn

If you have any other issues, please feel free to post in here.
Sreejith Sreenivasan 1,001 Reputation points

2023-08-16T11:11:04.4866667+00:00
@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

Here is my answers for your questions:

How did you migrate the Xamarin.Forms project to a MAUI project?

Yes I have used the .NET Upgrade Assistant Extension on VS. But I tried In-Place upgrade not side by side. I have a doubt on this session: My project is already available on stores. So if we create a new MAUI project using side by side and move all the files into it, is it approve by the stores?

You said add target in "ios project .csproj", is there a single project 's csproj file that includes TargetFrameworks element?

I have added the TargetFrameworks on iosproject.csproj file, not in the solution.csproj. <TargetFrameworks>net7.0-android;net7.0-ios</TargetFrameworks> this code is already available on solution.csproj file.

.NET MAUI6 was no longer supported. It's recommended that you try to use .NET7. Then check if the errors still exist.

I used .NET 6 for the Migration and I fixed the Cannot resolve type errors by setting the Xaml build action to MauiXaml from Embedded Resource.

The same issue as the second point, the target platforms element should be added into the single project's csproj file but not the iOS project's.

I don't have UWP app in my project then why the windows related issues are showing? Like you suggest the TargetFrameworks is already in my solution.

Please check the below screenshot:

I have fixed the Xamarin.AndroidX.Browser issue by installing a few NuGet packages on Android and solution project.

On Android:

<PackageReference Include="Xamarin.AndroidX.Browser"> <Version>1.4.0.1</Version> </PackageReference> <PackageReference Include="Xamarin.AndroidX.Lifecycle.LiveData"> <Version>2.4.1.1</Version> </PackageReference> <PackageReference Include="Xamarin.Google.Android.Material"> <Version>1.6.0</Version> </PackageReference> <PackageReference Include="Xamarin.AndroidX.Navigation.UI"> <Version>2.4.2</Version> </PackageReference>

On Solution:

<PackageReference Include="Xamarin.AndroidX.Browser" Version="1.4.0.1" /> <PackageReference Include="Xamarin.AndroidX.Lifecycle.LiveData" Version="2.4.1.1" /> <PackageReference Include="Xamarin.Google.Android.Material" Version="1.6.0" /> <PackageReference Include="Xamarin.AndroidX.Core" Version="1.8.0.1" /> <PackageReference Include="Xamarin.AndroidX.Navigation.UI" Version="2.4.2" />

And it looks like you are still using Xamarin.Essentials whose functionality is now part of MAUI as well. Please remove the Xamarin.Essentials NuGet package from your .NET Android or .NET iOS app and migrate Xamarin.Essentials code

Xamarin.Essentials package is not listing on my android or iOS project.

Are you suggesting to start Migration again using .NET 7? Or is it possible to Migrate to .NET 7 from 6? After migrating the solution using .NET 7 via side by side upgrade, do I need to upgrade the Android and iOS projects?
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-17T09:50:46.86+00:00
My project is already available on stores. So if we create a new MAUI project using side by side and move all the files into it, is it approve by the stores?

You could manage the app version, iOS distribution provision profile and Android keystore. Then publish the MAUI app from the next version. It's OK that you tried In-Place upgrade. I want to make sure there is no error or warning during the use of the upgrade assistant extension.

I don't have UWP app in my project then why the windows related issues are showing?

Please check if there is .net6.0-windows target framework element in your solution.csproj file.

Are you suggesting to start Migration again using .NET 7?

Yes. Since .NET6 is not supported, it's recommended that you try to use .NET7.

Or is it possible to Migrate to .NET 7 from 6?

Yes. If .NET7 workloads are installed in your machine, you could try to change .net6 to .net7 in the csproj file, then reload the project.

After migrating the solution using .NET 7 via side by side upgrade, do I need to upgrade the Android and iOS projects?

Yes. All these three projects need to be upgraded.

Other suggestions:

The outputtype should be Exe, not Library

You use GMImagePicker.Xamarin for iOS project, right? This third-party library doesn't support .net-ios. Please try to remove this library or connect the owners to support MAUI.

It looks like there is no issue for Android. You could try to edit the solution.csproj file to support Android only, then determine whether the current problem only exists on the iOS platform.
Sreejith Sreenivasan 1,001 Reputation points

2023-08-17T14:49:41.7466667+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

Using .NET7 I have upgraded the Xamarin Forms project to MAUI.

But I am getting below errors when rebuilding the project.

Severity Code Description Project File Line Suppression State Error NU1012 Platform version is not present for one or more target frameworks, even though they have specified a platform: net7.0-android MyProject.Android E:\My Projects\Xamarin.Net7\MyProject-app\MyProject\MyProject.Android\MyProject.Android.csproj 1

Severity Code Description Project File Line Suppression State Error NETSDK1139 The target platform identifier android was not recognized. MyProject C:\Program Files\dotnet\sdk\7.0.400\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.TargetFrameworkInference.targets 113

Severity Code Description Project File Line Suppression State Error NETSDK1139 The target platform identifier ios was not recognized. MyProject C:\Program Files\dotnet\sdk\7.0.400\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.TargetFrameworkInference.targets 113

I also tried the migration with .NET 8 and getting same above errors. Could you please a solution for this.

I feel this is happening due some kind of caches. Do I need to clear any kind of folders like bin and obj. Other than bin and obj do I need to delete any other cache folders for the proper working of the application? Somewhere I found need to clear the workloads under C:\Program Files\dotnet\metadata\workloads location.
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-18T06:54:27.72+00:00

Is .net7 workloads in C:\Program Files\dotnet\metadata\workload?

You could try to upgrade your original Xamarin.Forms project again and select .net7 as the target framework, pay attention to upgrading Xamarin.iOS/Android project before the Xamarin.Froms single project.

How did you build the project? Do you try to select an Android emulator then run on this device?

As I understood, you got the errors after running the app. You could close VS, deleted Bin, Obj, .vs folders, and check if there are any other errors.

In addition, please check Android /iOS project configuration, refer to Manually upgrade a Xamarin.Forms app to .NET MAUI - .NET MAUI | Microsoft Learn

Would you mind sharing a minimal reproducible sample with me?
Sreejith Sreenivasan 1,001 Reputation points

2023-08-21T10:55:11.2566667+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

Is .net7 workloads in C:\Program Files\dotnet\metadata\workload?

Yes workloads are present in dotnet folder.

You could try to upgrade your original Xamarin.Forms project again and select .net7 as the target framework, pay attention to upgrading Xamarin.iOS/Android project before the Xamarin.Froms single project.

I am always doing reverse, first I upgrade solution(single project) then Android, and finally iOS. As per your suggestion I did iOS first, then android and finally solution. At that time, iOS and Android upgrade is successful without any errors. But a few components are failed in solution upgrade.

How did you build the project? Do you try to select an Android emulator then run on this device?

I am using my physical device to run the application. But before running it to my device, clean and rebuild shows all these errors.

As I understood, you got the errors after running the app. You could close VS, deleted Bin, Obj, .vs folders, and check if there are any other errors.

I am always doing these steps before rebuilding the project.

In addition, please check Android /iOS project configuration, refer to Manually upgrade a Xamarin.Forms app to .NET MAUI - .NET MAUI | Microsoft Learn

There are a lot of initializations are present in my MainActivity and AppDelegate. So how all those will work if I remove it?

Would you mind sharing a minimal reproducible sample with me?

My issues are on a real project, so sharing demo is little tedious. Is it okay If I remove all the Xaml pages and shared a demo?
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-22T07:58:23.9466667+00:00

There are a lot of initializations are present in my MainActivity and AppDelegate. So how all those will work if I remove it?

You shouldn't remove them, please try to update the MainApplication class, and update the MainActivity class to inherit from MauiAppCompatActivity, update the AppDelegate class to inherit from MauiUIApplicationDelegate. Then modify the initializations in the OnCreate method or other methods.

My issues are on a real project, so sharing demo is little tedious. Is it okay If I remove all the Xaml pages and shared a demo?

For safety, it's not recommended that you share the real project with me. You could describe the error messages in detail or take some screenshots. If you want to share the real project and get the 1:1 support, you could open a paid phone support ticket.

In addition, do you still have the NETSDK1139, NU1012 errors?
Sreejith Sreenivasan 1,001 Reputation points

2023-08-22T15:35:31.3566667+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

In addition, do you still have the NETSDK1139, NU1012 errors?

Those errors are resolved after deleting the .vs folders

After updating the visual studio I tried to upgrade my fresh xamarin forms project to MAUI. First I migrated the solution(no errors), after updated android and ios projects. But I got one error on both android and ios projects.

Do you have any idea why 1 item is failing on android and iOS. This time first I convert the android and iOS project to SDK style. After that I upgrade the project using .NET 7.

How can we solve the Cannot resolve type "ContentPage" errors. I tried updating the build action to MauiXaml, but it is not working now. This is the main error I am always facing.

1>Views\User Pages\SignUpPage.xaml : error : : XamlC error XFC0000 : Cannot resolve type "ContentPage".

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Microsoft External Staff

Would you mind sharing this SignUpPage.xaml with me? or go to this page to check if there are any other errors? Or is it similar to the following example?

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="XXX.SignUpPage"
             Title="XX"
   BackgroundColor="White">
    <StackLay
        <!-- Other views go here -->
    </StackLayout>
</ContentPage>

Sreejith Sreenivasan 1,001 Reputation points

2023-08-23T10:18:46.3533333+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

I have uploaded the sign up pages here. Could you please check and let me know what is the issues ASAP?

After updating the visual studio I tried to upgrade my fresh xamarin forms project to MAUI. First I migrated the solution(no errors), after updated android and ios projects. But I got one error on both android and ios projects.

Any idea why these errors are happening? My VS version is 17.7.2 and upgrade assistant version is 0.5.261.51392.

Sreejith Sreenivasan 1,001

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

Other than Cannot resolve type "ContentPage" error I am facing other 6 errors. I am adding it below, could you please provide a solution ASAP.

1. Severity	Code	Description	Project	File	Line	Suppression State
Error	NU1201	Project MyProject is not compatible with net7.0 (.NETCoreApp,Version=v7.0). Project MyProject supports:
  - net7.0-android33.0 (.NETCoreApp,Version=v7.0)
  - net7.0-ios16.1 (.NETCoreApp,Version=v7.0)
  - net7.0-windows10.0.19041 (.NETCoreApp,Version=v7.0)	MyProject.iOS	E:\My Projects\Xamarin\.Net7\With latest vs - 54 errors\MyProject\MyProject\MyProject.iOS\MyProject.iOS.csproj	1	

2. Severity	Code	Description	Project	File	Line	Suppression State
Error		Project '..\MyProject\MyProject.csproj' targets 'net7.0-android;net7.0-ios;net7.0-windows10.0.19041.0'. It cannot be referenced by a project that targets '.NETCoreApp,Version=v7.0'.	MyProject.iOS	C:\Program Files\Microsoft Visual Studio\2022\Community\MSBuild\Current\Bin\amd64\Microsoft.Common.CurrentVersion.targets	1842	

3. Severity	Code	Description	Project	File	Line	Suppression State
Error		Project '..\MyProject\MyProject.csproj' targets 'net7.0-android;net7.0-ios;net7.0-windows10.0.19041.0'. It cannot be referenced by a project that targets '.NETCoreApp,Version=v7.0'.	MyProject.Android	C:\Program Files\Microsoft Visual Studio\2022\Community\MSBuild\Current\Bin\amd64\Microsoft.Common.CurrentVersion.targets	1842	

4. Severity	Code	Description	Project	File	Line	Suppression State
Error	APT2259	'textEnd' is incompatible with attribute iconGravity (attr) flags [start=1, textStart=2].	MyProject	E:\My Projects\Xamarin\.Net7\With latest vs - 54 errors\MyProject\MyProject\MyProject\res\layout\mtrl_calendar_month_navigation.xml	33	

5. Severity	Code	Description	Project	File	Line	Suppression State
Error	APT2061	failed linking file resources.	MyProject	C:\Program Files\dotnet\packs\Microsoft.Android.Sdk.Windows\33.0.68\tools\Xamarin.Android.Aapt2.targets	156	

6. Severity	Code	Description	Project	File	Line	Suppression State
Error	NU1201	Project MyProject is not compatible with net7.0 (.NETCoreApp,Version=v7.0). Project MyProject supports:
  - net7.0-android33.0 (.NETCoreApp,Version=v7.0)
  - net7.0-ios16.1 (.NETCoreApp,Version=v7.0)
  - net7.0-windows10.0.19041 (.NETCoreApp,Version=v7.0)	MyProject.Android	E:\My Projects\Xamarin\.Net7\With latest vs - 54 errors\MyProject\MyProject\MyProject.Android\MyProject.Android.csproj	1

Can you have a look If I provide you the real project with a single page? Without any private data I will prepare a demo with single page, so it will have all the issues. Because I need to migrate all of my projects to MAUI and I am stuck on the first one for a long time.

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-24T09:39:20.1433333+00:00

You could prepare a demo with single page. Please pay attention to protect your private information.
Sreejith Sreenivasan 1,001 Reputation points

2023-08-24T11:08:40.3233333+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

I have created demo projects with one page and uploaded here.

I have added 2 projects in this: One is the Xamarin forms original project and the other one is migrated MAUI project with .NET 7.

The MAUI project has same kind of issues that I face on the real project.
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-25T09:32:08.49+00:00
Hi @Sreejith Sreenivasan , I check the references of your project, there are many third-party tools. And some NuGet packages don't support MAUI, for example NuGet Gallery | Rg.Plugins.Popup 2.1.0. Some do not support .net7, for example NuGet Gallery | Xam.Plugin.Media 6.0.2 It seems to be the real reason. Please try to remove these packages and try to find if there are other packages that can replace them. Or you could connect the owners to update the package.

As described in the doc - Manually upgrade a Xamarin.Forms app to .NET MAUI - .NET MAUI | Microsoft Learn

If you can't find a .NET 6+ compatible version of a NuGet package you should:

Recompile the package with .NET TFMs, if you own the code.

Look for a preview release of a .NET 6+ version of the package.

Replace the dependency with a .NET 6+ compatible alternative.

In addition, it's recommended that you upgrade the project manually. You could create an empty MAUI project, then copy the file into it.
Sreejith Sreenivasan 1,001 Reputation points

2023-08-28T11:55:00.0566667+00:00
@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

I am working on the manual migration of the project, as suggested. I have created a new MAUI project and imported the existing login page into it. But there are a lot of errors due to the xamarin-related codes. Fixed a few issues, pending issues are:

Styles are not reading on the XAML pages.

LoginPage.xaml

I have added the styles on App.xaml.cs, but it is not reading.

Xaml widget names are not reading on Xaml.cs pages.

I have added x:Name for all these widgets, but these are not reading on the xaml.cs. How can I fix these issues?
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-29T09:37:32.22+00:00

For the first question, you could open the App.xaml file, there is a default theme, and all styles can be set in "Resources/Styles/Styles.xaml", please add the styles in Styles.xaml. For more details, please refer to Theme an app - .NET MAUI | Microsoft Learn

For the second question, there are two directions. There might be some other errors in the page.xaml, so the element cannot be read. Or this is a compiler error, you could try to clean the bin/obj folder, re-open VS and re-build the app.

I will make an answer that summarizes this thread, please avoid posting multiple questions in a single thread as noted in the Q&A FAQ: How to write a quality question. And you can create a new thread if you have any other issues, thanks for your understanding.

Accepted answer

0 additional answers

Your answer

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-17T09:50:46.86+00:00

My project is already available on stores. So if we create a new MAUI project using side by side and move all the files into it, is it approve by the stores?

You could manage the app version, iOS distribution provision profile and Android keystore. Then publish the MAUI app from the next version. It's OK that you tried In-Place upgrade. I want to make sure there is no error or warning during the use of the upgrade assistant extension.

I don't have UWP app in my project then why the windows related issues are showing?

Please check if there is .net6.0-windows target framework element in your solution.csproj file.

Are you suggesting to start Migration again using .NET 7?

Yes. Since .NET6 is not supported, it's recommended that you try to use .NET7.

Or is it possible to Migrate to .NET 7 from 6?

Yes. If .NET7 workloads are installed in your machine, you could try to change .net6 to .net7 in the csproj file, then reload the project.

After migrating the solution using .NET 7 via side by side upgrade, do I need to upgrade the Android and iOS projects?

Yes. All these three projects need to be upgraded.

Other suggestions:

The outputtype should be Exe, not Library

You use GMImagePicker.Xamarin for iOS project, right? This third-party library doesn't support .net-ios. Please try to remove this library or connect the owners to support MAUI.

It looks like there is no issue for Android. You could try to edit the solution.csproj file to support Android only, then determine whether the current problem only exists on the iOS platform.
Sreejith Sreenivasan 1,001 Reputation points

2023-08-17T14:49:41.7466667+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

Using .NET7 I have upgraded the Xamarin Forms project to MAUI.

But I am getting below errors when rebuilding the project.

Severity Code Description Project File Line Suppression State Error NU1012 Platform version is not present for one or more target frameworks, even though they have specified a platform: net7.0-android MyProject.Android E:\My Projects\Xamarin.Net7\MyProject-app\MyProject\MyProject.Android\MyProject.Android.csproj 1

Severity Code Description Project File Line Suppression State Error NETSDK1139 The target platform identifier android was not recognized. MyProject C:\Program Files\dotnet\sdk\7.0.400\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.TargetFrameworkInference.targets 113

Severity Code Description Project File Line Suppression State Error NETSDK1139 The target platform identifier ios was not recognized. MyProject C:\Program Files\dotnet\sdk\7.0.400\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.TargetFrameworkInference.targets 113

I also tried the migration with .NET 8 and getting same above errors. Could you please a solution for this.

I feel this is happening due some kind of caches. Do I need to clear any kind of folders like bin and obj. Other than bin and obj do I need to delete any other cache folders for the proper working of the application? Somewhere I found need to clear the workloads under C:\Program Files\dotnet\metadata\workloads location.
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-18T06:54:27.72+00:00

Is .net7 workloads in C:\Program Files\dotnet\metadata\workload?

You could try to upgrade your original Xamarin.Forms project again and select .net7 as the target framework, pay attention to upgrading Xamarin.iOS/Android project before the Xamarin.Froms single project.

How did you build the project? Do you try to select an Android emulator then run on this device?

As I understood, you got the errors after running the app. You could close VS, deleted Bin, Obj, .vs folders, and check if there are any other errors.

In addition, please check Android /iOS project configuration, refer to Manually upgrade a Xamarin.Forms app to .NET MAUI - .NET MAUI | Microsoft Learn

Would you mind sharing a minimal reproducible sample with me?
Sreejith Sreenivasan 1,001 Reputation points

2023-08-21T10:55:11.2566667+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

Is .net7 workloads in C:\Program Files\dotnet\metadata\workload?

Yes workloads are present in dotnet folder.

You could try to upgrade your original Xamarin.Forms project again and select .net7 as the target framework, pay attention to upgrading Xamarin.iOS/Android project before the Xamarin.Froms single project.

I am always doing reverse, first I upgrade solution(single project) then Android, and finally iOS. As per your suggestion I did iOS first, then android and finally solution. At that time, iOS and Android upgrade is successful without any errors. But a few components are failed in solution upgrade.

How did you build the project? Do you try to select an Android emulator then run on this device?

I am using my physical device to run the application. But before running it to my device, clean and rebuild shows all these errors.

As I understood, you got the errors after running the app. You could close VS, deleted Bin, Obj, .vs folders, and check if there are any other errors.

I am always doing these steps before rebuilding the project.

In addition, please check Android /iOS project configuration, refer to Manually upgrade a Xamarin.Forms app to .NET MAUI - .NET MAUI | Microsoft Learn

There are a lot of initializations are present in my MainActivity and AppDelegate. So how all those will work if I remove it?

Would you mind sharing a minimal reproducible sample with me?

My issues are on a real project, so sharing demo is little tedious. Is it okay If I remove all the Xaml pages and shared a demo?
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-22T07:58:23.9466667+00:00

There are a lot of initializations are present in my MainActivity and AppDelegate. So how all those will work if I remove it?

You shouldn't remove them, please try to update the MainApplication class, and update the MainActivity class to inherit from MauiAppCompatActivity, update the AppDelegate class to inherit from MauiUIApplicationDelegate. Then modify the initializations in the OnCreate method or other methods.

My issues are on a real project, so sharing demo is little tedious. Is it okay If I remove all the Xaml pages and shared a demo?

For safety, it's not recommended that you share the real project with me. You could describe the error messages in detail or take some screenshots. If you want to share the real project and get the 1:1 support, you could open a paid phone support ticket.

In addition, do you still have the NETSDK1139, NU1012 errors?
Sreejith Sreenivasan 1,001 Reputation points

2023-08-22T15:35:31.3566667+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

In addition, do you still have the NETSDK1139, NU1012 errors?

Those errors are resolved after deleting the .vs folders

After updating the visual studio I tried to upgrade my fresh xamarin forms project to MAUI. First I migrated the solution(no errors), after updated android and ios projects. But I got one error on both android and ios projects.

Do you have any idea why 1 item is failing on android and iOS. This time first I convert the android and iOS project to SDK style. After that I upgrade the project using .NET 7.

How can we solve the Cannot resolve type "ContentPage" errors. I tried updating the build action to MauiXaml, but it is not working now. This is the main error I am always facing.

1>Views\User Pages\SignUpPage.xaml : error : : XamlC error XFC0000 : Cannot resolve type "ContentPage".
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-23T09:33:21.4666667+00:00

Would you mind sharing this SignUpPage.xaml with me? or go to this page to check if there are any other errors? Or is it similar to the following example?

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="XXX.SignUpPage" Title="XX" BackgroundColor="White"> <StackLay  </StackLayout> </ContentPage>
Sreejith Sreenivasan 1,001 Reputation points

2023-08-23T10:18:46.3533333+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

I have uploaded the sign up pages here. Could you please check and let me know what is the issues ASAP?

After updating the visual studio I tried to upgrade my fresh xamarin forms project to MAUI. First I migrated the solution(no errors), after updated android and ios projects. But I got one error on both android and ios projects.

Any idea why these errors are happening? My VS version is 17.7.2 and upgrade assistant version is 0.5.261.51392.
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-24T09:39:20.1433333+00:00

You could prepare a demo with single page. Please pay attention to protect your private information.
Sreejith Sreenivasan 1,001 Reputation points

2023-08-24T11:08:40.3233333+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

I have created demo projects with one page and uploaded here.

I have added 2 projects in this: One is the Xamarin forms original project and the other one is migrated MAUI project with .NET 7.

The MAUI project has same kind of issues that I face on the real project.
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-25T09:32:08.49+00:00

Hi @Sreejith Sreenivasan , I check the references of your project, there are many third-party tools. And some NuGet packages don't support MAUI, for example NuGet Gallery | Rg.Plugins.Popup 2.1.0. Some do not support .net7, for example NuGet Gallery | Xam.Plugin.Media 6.0.2 It seems to be the real reason. Please try to remove these packages and try to find if there are other packages that can replace them. Or you could connect the owners to update the package.

As described in the doc - Manually upgrade a Xamarin.Forms app to .NET MAUI - .NET MAUI | Microsoft Learn

If you can't find a .NET 6+ compatible version of a NuGet package you should:

Recompile the package with .NET TFMs, if you own the code.

Look for a preview release of a .NET 6+ version of the package.

Replace the dependency with a .NET 6+ compatible alternative.

In addition, it's recommended that you upgrade the project manually. You could create an empty MAUI project, then copy the file into it.
Sreejith Sreenivasan 1,001 Reputation points

2023-08-28T11:55:00.0566667+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.)

I am working on the manual migration of the project, as suggested. I have created a new MAUI project and imported the existing login page into it. But there are a lot of errors due to the xamarin-related codes. Fixed a few issues, pending issues are:

Styles are not reading on the XAML pages.

LoginPage.xaml

I have added the styles on App.xaml.cs, but it is not reading.

Xaml widget names are not reading on Xaml.cs pages.

I have added x:Name for all these widgets, but these are not reading on the xaml.cs. How can I fix these issues?
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,416 Reputation points Microsoft External Staff

2023-08-29T09:37:32.22+00:00

For the first question, you could open the App.xaml file, there is a default theme, and all styles can be set in "Resources/Styles/Styles.xaml", please add the styles in Styles.xaml. For more details, please refer to Theme an app - .NET MAUI | Microsoft Learn

For the second question, there are two directions. There might be some other errors in the page.xaml, so the element cannot be read. Or this is a compiler error, you could try to clean the bin/obj folder, re-open VS and re-build the app.

I will make an answer that summarizes this thread, please avoid posting multiple questions in a single thread as noted in the Q&A FAQ: How to write a quality question. And you can create a new thread if you have any other issues, thanks for your understanding.

Answer 1

Hello,

I check the references of your project, there are many third-party tools. And some NuGet packages don't support MAUI, for example NuGet Gallery | Rg.Plugins.Popup 2.1.0. Some do not support .net7, for example NuGet Gallery | Xam.Plugin.Media 6.0.2. Please try to remove these packages and try to find if there are other packages that can replace them. Or you could connect the owners to update the package.

As described in the doc - Manually upgrade a Xamarin.Forms app to .NET MAUI - .NET MAUI | Microsoft Learn

If you can't find a .NET 6+ compatible version of a NuGet package you should:

Recompile the package with .NET TFMs, if you own the code.
Look for a preview release of a .NET 6+ version of the package.
Replace the dependency with a .NET 6+ compatible alternative.

In addition, it's recommended that you upgrade the project manually. You could create an empty MAUI project, then copy the file into it.

Update

I have added the styles on App.xaml.cs, but it is not reading.

You could open the App.xaml file, there a default theme, and all styles can be set in "Resources/Styles/Styles.xaml". For more details, please refer to Theme an app - .NET MAUI | Microsoft Learn

Xaml widget names are not reading on Xaml.cs pages.

There might be some other errors in the page.xaml, so the element cannot be read. Or this is a compilation error, you could try to clean the bin/obj folder, re-open VS and re-build the app.

Best Regards,

Wenyan Zhang

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