Can't Create Winform project

[Jesse Humphreys]

Hey all! 

When i first installed this, i messed around with it for a few hours and nothing seemed amiss... Que to today when i attempt to go create a new winform project targeting .net framework 4.8, i am constantly met with this:

System.NullReferenceException: Object reference not set to an instance of an object.

   at Microsoft.Templates.Core.Gen.GenController.ValidateUserSelection(UserSelection userSelection, Boolean isNewProject)

   at Microsoft.Templates.Core.Gen.NewProjectGenController.<UnsafeGenerateProjectAsync>d__4.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at Syncfusion.Templates.UI.Services.GenerationService.<GenerateProjectAsync>d__5.MoveNext()

I have tried uninstalling/reinstalling the suite, extensions, and even vs 2026 with no success at this point. The only thing that "sort of" works is creating a .net 10 targeted project and rolling it back to target win481, but then half of the controls throw some exception and either 
A: Never show up
B: Never let me save the form, or delete the control!

The latter (B) usually winds up with me having to restart visual studio entirely and lose any progress i had made..

Any advice? :')

[Yuvaraj Masilamani]

Hi Jesse Humphreys,

Thanks for reporting this issue.

To help us investigate further, could you please confirm which specific control you encountered this problem with?
This will allow us to narrow down the cause and provide the correct fix or workaround.

Additionally, if possible, please share:

• The exact control name(s) that fail to save
• Whether you’re using the Syncfusion WinForms Controls or a different control set
• Any additional stack traces or error messages that appear when the form fails to save

Once we have this information, we’ll be able to assist you more accurately.

[Jesse Humphreys]

Sadly i can not, Nww every winforms project, no matter the runtime targeted (.net 8, .net9, .net10, framework4.8, framework 4.6.2), provides the error above, and never actually sets up the project, therebuy rendering this near useless to me.. At least on the trial it somewhat worked, but once uninstalled and reinstalled using my community license, winform project as a whole are broken and do not work. 

"System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.Templates.Core.Gen.GenController.ValidateUserSelection(UserSelection userSelection, Boolean isNewProject)
   at Microsoft.Templates.Core.Gen.NewProjectGenController.<UnsafeGenerateProjectAsync>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Syncfusion.Templates.UI.Services.GenerationService.<GenerateProjectAsync>d__5.MoveNext()"

[Jesse Humphreys]

Heres a new one while attempting to add syncfusion references to a regular winformsproject: 

=====================
2026-03-30 11:08:31 PM
LimitedFunctionality
System.AggregateException: One or more errors occurred.
---> (Inner Exception #0) System.ArgumentException: An element with the same key but a different value already exists. Key: 'df2df817-f3d7-4008-07a3-1cc388707d83'
   at System.Collections.Immutable.ImmutableDictionary`2.HashBucket.Add(TKey key, TValue value, IEqualityComparer`1 keyOnlyComparer, IEqualityComparer`1 valueComparer, KeyCollisionBehavior behavior, OperationResult& result)
   at System.Collections.Immutable.ImmutableDictionary`2.Add(TKey key, TValue value, KeyCollisionBehavior behavior, MutationInput origin)
   at System.Collections.Immutable.ImmutableDictionary`2.Add(TKey key, TValue value)
   at Microsoft.VisualStudio.ProjectSystem.VS.Setup.SetupComponentRegistrationService.<>c.<RegisterProjectAsync>b__12_0(ImmutableDictionary`2 dic, Guid projectGuid)
   at System.Collections.Immutable.ImmutableInterlocked.Update[T,TArg](T& location, Func`3 transformer, TArg transformerArgument)
   at Microsoft.VisualStudio.ProjectSystem.VS.Setup.SetupComponentRegistrationService.<RegisterProjectAsync>d__12.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.ProjectSystem.VS.Setup.SetupComponentProvider.<InitializeCoreAsync>d__10.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.ProjectSystem.OnceInitializedOnceDisposedAsync.<<-ctor>b__9_0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.Threading.AwaitExtensions.ExecuteContinuationSynchronouslyAwaiter`1.GetResult()
   at Microsoft.VisualStudio.Threading.AsyncLazy`1.<>c__DisplayClass20_0.<<GetValueAsync>b__0>d.MoveNext()
<--- (Inner Exception #0)
===================

[Jesse Humphreys]

So i actually FINALLY got it working again, the downside is had to nuke essentially all my visual studio extensions 😅

- Uninstaller syncfusion extensions via visual studio

- Cleaned up GAC via syncfusion application

- Wiped my temp folder of any visual studio/syncfusion traces 

- Rebooted 

- Reinstalled syncfusion via nuget manager

- THEN reinstalled via syncfusion app and voila! We're working again.

For info's sake: running on visual studio 2026 community edition, always up to date. 

Running extensions: Re-Sharper, dotCover,DotMemory, roslynator,  Visual assist, copilot, http file generator, and a couple others 

Latest syncfusion (33.something)

Now only a couple controls complain about some missing reference but ya know what, ill take it! 

[EdbergVasan DallasVaz]

Hi Jesse Humphreys,

After installing the Syncfusion WinForms Template Studio extension, we were able to create both standard WinForms projects and Syncfusion WinForms projects in Visual Studio Community without issue. We could not reproduce the reported problem—projects are being created successfully across all framework options on our end. Could you please provide the additional details below so we can investigate further?

1. In Visual Studio, go to Extensions -> Manage Extensions -> Installed and search for the Syncfusion extensions by providing the keyword “syncfusion" in the search box. Share the screenshot of that dialog.
2. Could you please share the OS details on your machine
3. Gather log file. Please follow the steps in the link to get the Gather log file.
4. Additionally, as you mentioned, a few controls are missing references. Could you please list the control names so that we can share the references?

[David Jenkins]

Looks like a Syncfusion template issue, not your code. Try uninstalling it completely, clearing Visual Studio cache, and reinstalling the correct version for .NET Framework 4.8. If it still happens, it’s probably a bug in the extension and worth reporting to Syncfusion.

[Paul Bonham]

new install of visual Studio 2026 pro and full new install of syncfusion community 33.2.3 Tried to create a new winforms project using syncfusion installed location with C# and .NET 10.0. I selected blank project type and blank page. Did not select MSIX Packaging. Worked for me, but if I select a different drive for my project to be installed in I get :

System.NullReferenceException: Object reference not set to an instance of an object.

   at Microsoft.Templates.Core.Gen.GenController.ValidateUserSelection(UserSelection userSelection, Boolean isNewProject)

   at Microsoft.Templates.Core.Gen.NewProjectGenController.<UnsafeGenerateProjectAsync>d__4.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at Syncfusion.Templates.UI.Services.GenerationService.<GenerateProjectAsync>d__5.MoveNext()

[Suvetha Venkatesan]

Hi Paul Bonham,

Thank you for reaching out to us. We understand that you're experiencing an issue when selecting a different drive for your project.

We installed Syncfusion Community Edition 33.2.3 in Visual Studio 2026 Professional and created WinForms project by selection different project paths (other than C:) as the project location. In our testing, the project creation was completed successfully, and we could not able to reproduce the issue.

To help us investigate further, could you please share:

• The exact project path you selected for project creation.
• Any additional steps or settings you applied during project creation.
• Kindly check that you have full read/write permissions on the drive (for example, try manually creating a folder and file there).
• Kindly confirm Whether the drive is internal, external, or network based.
• Your Windows version and whether Visual Studio was run with administrator privileges.

Regards,
Suvetha Venkatesan.