.Net9 causing Could not find the type 'ObjCRuntime.__Registrar__

[tj-devel709]

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Issue moved from dotnet/maui#27312

• Please respond to @natevarghese.

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From @natevarghese on Thursday, January 23, 2025 6:18:01 PM

Description

After updating all my projects to .NET 9, I encountered the following error when trying to access a custom Objective-C binding library, which is referenced by the iOS project. The issue only occurs on a physical iOS device:

Error:
Could not find the type 'ObjCRuntime.Registrar' in the assembly.

Following suggestions, I added the recommended configuration to one or more of the referenced projects, as described in the release notes:

Source: Xamarin .NET 9 Release Notes - Type Registrar

<Target Name="SelectStaticRegistrar" AfterTargets="SelectRegistrar">
  <PropertyGroup Condition="'$(Registrar)' == 'managed-static'">
    <Registrar>static</Registrar>
  </PropertyGroup>
</Target>

After making this change, the app crashes immediately on startup, preventing me from obtaining a stack trace. I'm unsure how to proceed. I’ve added the snippet to the iOS project, the binding library project(s), and every possible combination of them, but the issue persists.

Steps to Reproduce

No response

Link to public reproduction project repository

No response

Version with bug

9.0.0 GA

Is this a regression from previous behavior?

No, this is something new

Last version that worked well

8.0.3 GA

Affected platforms

iOS

Affected platform versions

No response

Did you find any workaround?

No workarounds known

Relevant log output

[tj-devel709]

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Issue moved from dotnet/maui#27312

• Please respond to @Ying-6.

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From @Ying-6 on Friday, January 24, 2025 9:09:39 AM

Could you provide a simple reproduction project for us to investigate it further? Looking forward to your reply!

[tj-devel709]

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Issue moved from dotnet/maui#27312

• Please respond to @natevarghese.

---

From @natevarghese on Saturday, January 25, 2025 10:10:52 AM

Please use this as a test repo. It has the objc bindings already so it's quite large but not a lot of code is required to reproduce it.
https://github.com/natevarghese/Solution1

As a reminder it only crashes on physical iOS devices, so you will need to update the bundle identifier to one you have provisioned.

[tj-devel709]

Hi, moving the issue here. Let me know if this one should be in the Maui Issues!

[natevarghese]

Any update on this? Please do not archive it for inactivity

[Kalibrate-nvarghese]

@Ying-6 Any updates?

[rolfbjarne]

Following suggestions, I added the recommended configuration to one or more of the referenced projects, as described in the release notes:

Source: Xamarin .NET 9 Release Notes - Type Registrar

Can you get an MSBuild binlog from the build of the main project (app project) with this workaround applied?

[natevarghese]

@rolfbjarne

I generated msbuild.binlog using the following command:
dotnet build iOSApp1.csproj /bl:msbuild.binlog

The file has been added to the repository
https://github.com/natevarghese/Solution1/blob/master/msbuild.binlog

[rolfbjarne]

This is probably a dup of #21891, which has already been fixed (and the fix was released a couple of weeks ago - https://github.com/xamarin/xamarin-macios/releases/tag/dotnet-9.0.1xx-xcode16.2-9173)

Can you try removing the workaround, updating to the latest version of the iOS workload, and then try again to see if that works?

[natevarghese]

Yes, updating to the latest workload solved it. Thanks!