Make your addin registry free in .NET8.0 - Inventor 2025

[krzysztof_kuczmarski1]

Hi,

I'm developing an Inventor 2025 addin using .NET 8.0, and I’d like to make it registry-free.

In previous versions using .NET Framework 4.8, it was possible to create a registry-free COM addin by using a .manifest file with a clrClass entry.

However, I'm not sure if this method still works with .NET 8.0 (since clrClass seems to be tied to .NET Framework).

Is there any known way to make a registry-free COM addin for Inventor 2025 using .NET 8.0?

If not, what’s the recommended way to register the COM class so that Inventor can load the addin properly?

Thanks in advance!

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">

  <assemblyIdentity name="Bimet2025" version="1.0.0.0"></assemblyIdentity>

  <clrClass clsid="{b9382b4e-394c-4567-bfe5-38f303ded113}" progid="Bimet2025.StandardAddInServer" threadingModel="Both" name="Bimet2025.StandardAddInServer" runtimeVersion=""></clrClass>

  <file name="AddinBimet.dll" hashalg="SHA1"></file>

</assembly>

[jjstr8]

You don't need a manifest file.  See this link - Is a Manifest necessary? 

Also, @JelteDeJong has a good step-by-step tutorial on his website.

Creating an addin (Inventor 2025 and later) 

[krzysztof_kuczmarski1]

Thanks for your reply. 
My addin was used by several people in my company. The installation was simple, because we just copied the compiled files to the Addins folder and everything worked. Recently we upgraded Inventor to version 2025 and I updated the addin to .NET 8.0 using @JelteDeJong tutorial. On my computer where I compile an addin everything works as it should, however on others we have problems. The addin is loaded and some things work, others don't throwing the exception.
Tomorrow I will post the exception that is throw constantly, from what I read it is related to COM registry.
Any suggestions in the meantime would be appreciated!

[krzysztof_kuczmarski1]

Hi, as I promised this is the exception thrown by many methods:

See the end of this message for details on invoking 
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.InvalidOperationException: Failed initializing notifications
 ---> System.IO.IOException: Cannot create a stable subkey under a volatile parent key.
   at Microsoft.Win32.RegistryKey.Win32Error(Int32 errorCode, String str)
   at Microsoft.Win32.RegistryKey.CreateSubKey(String subkey, RegistryKeyPermissionCheck permissionCheck, RegistryOptions registryOptions)
   at Microsoft.Toolkit.Uwp.Notifications.ToastNotificationManagerCompat.Initialize()
   at Microsoft.Toolkit.Uwp.Notifications.ToastNotificationManagerCompat..cctor()
   --- End of inner exception stack trace ---
   at Microsoft.Toolkit.Uwp.Notifications.ToastNotificationManagerCompat.CreateToastNotifier()
   at Microsoft.Toolkit.Uwp.Notifications.ToastContentBuilder.Show(CustomizeToast customize)
   at Microsoft.Toolkit.Uwp.Notifications.ToastContentBuilder.Show()
   at Bimet2025.Save_form_bimet.ShowToastNotification(String title, String content) in C:\Moje Programy\Bimet Inventor Addin 2025\Bimet inventor addin 2025\WinFormsApp1\6 Dialog zapisu.cs:line 581
   at Bimet2025.Save_form_bimet.updateAll() in C:\Moje Programy\Bimet Inventor Addin 2025\Bimet inventor addin 2025\WinFormsApp1\6 Dialog zapisu.cs:line 232
   at Bimet2025.Save_form_bimet.comboBox_Type_SelectedIndexChanged(Object sender, EventArgs e) in C:\Moje Programy\Bimet Inventor Addin 2025\Bimet inventor addin 2025\WinFormsApp1\6 Dialog zapisu.cs:line 629
   at System.Windows.Forms.ComboBox.OnSelectedIndexChanged(EventArgs e)
   at System.Windows.Forms.ComboBox.set_SelectedIndex(Int32 value)
   at Bimet2025.Save_form_bimet.populateProjektTypeComboBox(ComboBox comboBox) in C:\Moje Programy\Bimet Inventor Addin 2025\Bimet inventor addin 2025\WinFormsApp1\6 Dialog zapisu.cs:line 217
   at Bimet2025.Save_form_bimet..ctor() in C:\Moje Programy\Bimet Inventor Addin 2025\Bimet inventor addin 2025\WinFormsApp1\6 Dialog zapisu.cs:line 58
   at Bimet2025.BimetMain.button_SaveFormOpen_Click(Object sender, EventArgs e) in C:\Moje Programy\Bimet Inventor Addin 2025\Bimet inventor addin 2025\WinFormsApp1\4 BimetMain.cs:line 792
   at System.Windows.Forms.Button.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(HWND hWnd, MessageId msg, WPARAM wparam, LPARAM lparam)

[jjstr8]

@krzysztof_kuczmarski1 - This looks to be an issue with the Windows Community Toolkit. Unfortunately, I don't see where it's been resolved.

ToastNotificationManagerCompat: Cannot create a stable subkey under a volatile parent key #4858 

Also, for clarification, this is unrelated to a "registry-free addin". A registry-free addin is where your dll does not need to be registered with Windows. By default, Visual Studio embeds the manifest in your addin dll, so the separate .manifest file is not required.