How to fix this issue - Failed to marshal the Objective-C object 0x1257d5880

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Answer to: MAUI iOS Error – Failed to marshal the Objective-C object

Hi,

Thank you for sharing the detailed error log. I’ll explain what’s happening and how to fix it.

⚠️

Summary of the Error:

The issue occurs when MAUI attempts to marshal a native iOS object (UIView) to its corresponding managed .NET object:

Microsoft.Maui.Controls.Handlers.Items.VerticalCell

The error message says:

“Could not find an existing managed instance for this object, nor was it possible to create a new managed instance because the type ‘VerticalCell’ does not have a constructor that takes one NativeHandle argument.”

🧠

Root Cause:

MAUI uses reflection to construct managed instances of native objects. If a class like VerticalCell doesn’t define a constructor that accepts a NativeHandle (i.e., IntPtr), it cannot properly marshal the native object, and the app crashes.

✅

Solutions:

1.

Make Sure You’re Using the Latest MAUI Version

Older versions of .NET MAUI had bugs related to handlers and object marshalling. Update your workloads:

dotnet workload update

Also, update all related NuGet packages.

2.

Add the Missing Constructor to VerticalCell

If you’re using a custom VerticalCell class, it must include a constructor like this:

public VerticalCell(IntPtr handle) : base(handle)

{

    // Optional initialization

}

Or this more complete version:

public VerticalCell(IntPtr handle, bool owns) : base(handle, owns)

{

    // Optional initialization

}

This allows MAUI to correctly bind the native view.

3.

Check Compatibility of FFImageLoading

Your stack trace shows involvement from:

FFImageLoading.Maui.Platform.CachedImageHandler

Make sure that:

• You are using a version of FFImageLoading compatible with your MAUI version.
• Or consider migrating to CommunityToolkit.Maui which is actively maintained and MAUI-ready.

4.

Handler Initialization

If you’re manually registering handlers in MauiProgram.cs, double-check how the ItemsViewHandler or custom handlers are set up. Improper registration may cause such issues.

🧪 Example Fix (for custom VerticalCell):

public class VerticalCell : ViewCell

{

    public VerticalCell(IntPtr handle) : base(handle)

    {

    }

    public VerticalCell()

    {

    }

}

✅

Conclusion:

The crash occurs because MAUI can’t instantiate a managed wrapper for a native iOS view due to a missing constructor. To fix it:

• Add the required IntPtr constructor to your class.
• Ensure all libraries (especially FFImageLoading) are compatible.
• Keep your MAUI environment and dependencies up to date.

Let me know if you’d like me to share a working example or help troubleshoot further. Good luck!

Feel free to copy and paste this directly into your answer on Microsoft Learn. Let me know if you’d like a shorter or simplified version too!Sure! Here’s the organized and accurate English response you can use to reply to the question on Microsoft Learn:

✅ 

Answer to: MAUI iOS Error – Failed to marshal the Objective-C object

Hi,

Thank you for sharing the detailed error log. I’ll explain what’s happening and how to fix it.

⚠️ 

Summary of the Error:

The issue occurs when MAUI attempts to marshal a native iOS object (UIView) to its corresponding managed .NET object:

Microsoft.Maui.Controls.Handlers.Items.VerticalCell

The error message says:

“Could not find an existing managed instance for this object, nor was it possible to create a new managed instance because the type ‘VerticalCell’ does not have a constructor that takes one NativeHandle argument.”

🧠 

Root Cause:

MAUI uses reflection to construct managed instances of native objects. If a class like VerticalCell doesn’t define a constructor that accepts a NativeHandle (i.e., IntPtr), it cannot properly marshal the native object, and the app crashes.

✅ 

Solutions:

1. 

Make Sure You’re Using the Latest MAUI Version

Older versions of .NET MAUI had bugs related to handlers and object marshalling. Update your workloads:

dotnet workload update

Also, update all related NuGet packages.

2. 

Add the Missing Constructor to VerticalCell

If you’re using a custom VerticalCell class, it must include a constructor like this:

public VerticalCell(IntPtr handle) : base(handle)

{

    // Optional initialization

}

Or this more complete version:

public VerticalCell(IntPtr handle, bool owns) : base(handle, owns)

{

    // Optional initialization

}

This allows MAUI to correctly bind the native view.

3. 

Check Compatibility of FFImageLoading

Your stack trace shows involvement from:

FFImageLoading.Maui.Platform.CachedImageHandler

Make sure that:

• You are using a version of FFImageLoading compatible with your MAUI version.
• Or consider migrating to CommunityToolkit.Maui which is actively maintained and MAUI-ready.

4. 

Handler Initialization

If you’re manually registering handlers in MauiProgram.cs, double-check how the ItemsViewHandler or custom handlers are set up. Improper registration may cause such issues.

🧪 Example Fix (for custom VerticalCell):

public class VerticalCell : ViewCell

{

    public VerticalCell(IntPtr handle) : base(handle)

    {

    }

    public VerticalCell()

    {

    }

}

✅ 

Conclusion:

The crash occurs because MAUI can’t instantiate a managed wrapper for a native iOS view due to a missing constructor. To fix it:

• Add the required IntPtr constructor to your class.
• Ensure all libraries (especially FFImageLoading) are compatible.
• Keep your MAUI environment and dependencies up to date.

Let me know if you’d like me to share a working example or help troubleshoot further. Good luck!

Feel free to copy and paste this directly into your answer on Microsoft Learn. Let me know if you’d like a shorter or simplified version too!