Cannot create Syncfusion project for C#, "Templates.UI error

[Richard Krol]

Good day to all!

When attempting to create a new "Syncfusion Windows Forms Template Studio" project, I receive following error:

"Error: this template attempted to load component assembly 'Syncfusion.Windorms.Tempates.UI, Version=39.1.33, Culture=neutral, Public Key token.... Form more information on this problem and how to enable this template, please see documentation on Customizing Project Templates."

Steps:

1. Open VS 2022 Pro
2. click on "Create a new project"
3. Choose "Syncfusion Windows Forms Template Studio", click next.
   
   
   
4. Name project, local, solution name... click Create.
5. Receive following error...
   
   
   
6. This same error, occurs if in a project and attempting to "Add Syncfusion Form..." to my project.

What I've Tried to resolve...

• reload (run) assemblies
• re-install sync fusion
  
• cleaned out obj, temp files
• numerous restarts

Running on Windows 11, VS 2022.

Somewhat new to the Syncfusion family, looked at forums, couldn't find much on this exact error but looked at similar forums for attempting to resolve but didn't find much.  

Thanks for looking at this!

[Aleksandar]

I've got exactly the same with Blazor template... Help us, please. :) 

[Kesavaraman Venkadesan]

Hi Aleksandar,

Thank you for reaching out and sharing the screenshots. We understand you're experiencing error while creating a project using our Syncfusion WinForms and Blazor Template Studio extension. We appreciate your patience and cooperation as we work to resolve this issue together.

Possible Cause:

The Syncfusion WinForms and Blazor extension may not have been installed properly in Visual Studio.

Solution:

Please follow these steps to uninstall and reinstall the extension:

Step 1: Uninstall Existing Syncfusion Extensions

1. Open Visual Studio 2022 → Extensions → Manage Extensions → Installed.
2. Search for "Syncfusion" and uninstall all related extensions.
3. Close Visual Studio and let the VSIX Installer complete the removal.
4. Manually delete leftover Syncfusion files from these locations:
1. %localappdata%\Microsoft\VisualStudio\{17.0_xxx}\Extensions\
2. {Visual Studio Install Path}\Common7\IDE\Extensions\

Step 2: Reinstall the Blazor and WinForms Extension

Option 1: Install from Syncfusion Setup

1. For to install Blazor extension, navigate to below location:

·       C:\Program Files (x86)\Syncfusion\Essential  Studio\Blazor\$YourBuildVERSION$\Utilities\Extensions\VS2022\

·       Double-click Syncfusion Blazor Template Studio.vsix to install.

2. For to install WinForms extension, navigate to below location:

·       C:\Program Files (x86)\Syncfusion\Essential Studio\Windows\$YourBuildVERSION$\Utilities\Extensions\VS2022\

·       Double-click Syncfusion WinForms Template Studio.vsix to install.

3. If needed, install other Syncfusion platform extensions from their respective setup directories (WPF, Maui, EJ2 Core etc.).

Option 2: Install via Visual Studio Marketplace

1. Open Visual Studio → Extensions → Manage Extensions → Online.
2. Search for " Blazor Extension - Syncfusion" and “WinForms Extension - Syncfusion” install it.

If the Issue Persists

Please provide:

• A screenshot of installed Syncfusion extensions (Extensions → Manage Extensions → Installed).
• A short video demonstrating the issue.
• Visual Studio version details (Help → About Microsoft Visual Studio → Copy Info).
• Gather log file. Please follow the steps in the link  to get the Gather log file.

Let us know if you need further assistance.

Best Regards,
V. Kesavaraman

[Aleksandar]

Thank you for the quick response. However, I wasn't able to follow the procedure you described.

Step 1 that you mentioned says:

Step 1: Uninstall Existing Syncfusion Extensions

Open Visual Studio 2022 → Extensions → Manage Extensions → Installed.

Search for "Syncfusion" and uninstall all related extensions.

As you can see in the screenshot of my Visual Studio (the latest update), there are no Syncfusion extensions listed under Manage Extensions → Installed.



However, they do appear in the menu itself.

Additionally, I’d like to mention that I installed Syncfusion Blazor using the Syncfusion Essential Studio Control Panel 29.1.33.

Can you tell me how it can be uninstalled in that case?

[Kesavaraman Venkadesan]

Hi Aleksandar,

Thank you for sharing the screenshots. It looks like you haven't searched for the Syncfusion extensions using the "Syncfusion" keyword in the Installed tab. Could you please try searching with that keyword and let us know if you find anything?

If the Syncfusion extensions still do not appear in the Installed tab but are visible in the menu, this could be due to cache. To resolve this, please follow the step below to clear the cache:

1. Manually delete any leftover Syncfusion Extension related files from the following locations:

• %localappdata%\Microsoft\VisualStudio\{17.0_xxx}\Extensions\
• {Visual Studio Install Path}\Common7\IDE\Extensions\

Let us know if this helps or if you encounter any issues.

Regards,

V. Kesavaraman

[David]

I've confirmed that this is indeed an issue. 

Even after fully updating Visual Studio, the problem persists. I also verified that searching for extensions doesn't locate it. The software was installed using syncfusionessentialstudiowebinstaller.exe, and I could only uninstall it through Add or Remove Programs. After uninstalling, no residual files remain in the two directories you mentioned.

This issue is currently blocking our progress. Please provide guidance on how to proceed. 

[Kesavaraman Venkadesan]

Hi David,

Thanks for your update. We understand the issue persists despite following the suggested steps. We are not able to reproduce the issue from our end. To help resolve this quickly, would it be possible to schedule a web meeting? Please let us know your availability.

Looking forward to your response.

Regards,

V. Kesavaraman

[Aleksandar]

Regarding what Kesavaraman Venkadesan said, I did perform a search in the "Installed" tab, and there are no Syncfusion extensions listed there. I would also like to emphasize again that the Syncfusion extension appears in the Extensions menu itself, as shown in the screenshot — not in the Installed tab, but directly in the menu. In the menu, there is no option to uninstall it.

Additionally, I’d like to explain that this issue didn’t just appear now. Let me try to describe the problem from the beginning.

Several months ago, I first installed Syncfusion Essential Studio Control Panel 28.1.33 (Main Release).
There were no previously installed Syncfusion products. At that point, everything worked correctly.

However, when I updated the Syncfusion Control Panel to the next version — 28.2.3 — the same problem appeared.
I should note that I only installed Blazor. That was the first time I saw this message.

My solution was to uninstall the entire product and then reinstall version 28.1.33 (Main Release). After that, the templates started working again.

My conclusion is that there are two issues, both related to the installation process of Syncfusion Essential Studio Control Panel:

1. The problem occurs when updating the Control Panel. During the update, the old version is not fully removed, and that causes issues.

2. Additionally, when Syncfusion Essential Studio Control Panel is installed, no Syncfusion extensions appear under Extensions → Installed, but instead they are only visible in the Extensions menu itself, as shown in the screenshot.

As a temporary solution, I’ll try the following:

1. Completely uninstall Syncfusion Essential Studio Control Panel

2. Manually delete any remaining Syncfusion files from these folders:

   • %localappdata%\Microsoft\VisualStudio\{17.0_xxx}\Extensions\

   • {Visual Studio Install Path}\Common7\IDE\Extensions\

3. Reinstall the latest version of Syncfusion Essential Studio Control Panel

I believe this might work and could serve as a temporary workaround.
However, when a new version is released, this whole process will likely need to be repeated.

I hope this information helps you find a long-term solution to the issue.

Regards,
Aleksandar

[Kesavaraman Venkadesan]

Hi Aleksandar,

Thank you for providing the detailed information. We understand that the issue occurs when updating the setup to a newer version by uninstalling the older one. This is a known issue on our end, and it appears to be related to cached extension data. We are currently investigating the matter to prevent errors when creating projects from our extension.

To stay updated on the progress, please follow the feedback link below:

Feedback: https://www.syncfusion.com/feedback/66938/need-to-resolve-extension-cache-issue-while-update-the-extension-to-latest

Regards,

V. Kesavaraman

[Kesavaraman Venkadesan]

Hi Aleksandar,

Query:  The problem occurs when updating the Control Panel. During the update, the old version is not fully removed, and that causes issues.

Response: To further investigate the issue regarding the Control Panel update, could you please share more details on your observation that the old version is not fully removed? Specifically, it would be helpful if you could provide:

1. Please share the log files using the Gather Log tool provided in the link below, so that we can investigate the reported issue further: 
   
   [Gather Log File](https://support.syncfusion.com/kb/article/2865/gather-log-file
2. Screenshot of the Windows OS version(Run-> Type ‘winver’),
3. Screenshot of the issue.

 

 Let us know any concerns.

Regards,

V. Kesavaraman

[Richard Krol]

As a comment being the original OP on this, Kesavaraman Venkadesan's procedure worked for me.

One step I added after step 1, 4b, I used a cleaning tool to clean temp directories and stale reg entries.  After a reboot, and reinstall, this worked fine for my WinForms.  I tested a simple Blazor project and worked fine as well.

For me I'll consider this closed for my issue, continue to help the others if needed on this thread.

Thank you for the support!

[Kesavaraman Venkadesan]

Hi Richard,

We are glad to know that both your WinForms and Blazor projects are now working as expected. If you need any further assistance, please feel free to reach out. We’re always here to help! Therefore, we are marking this thread as solved.

Regards,

V. Kesavaraman

[David]

I'm wondering if the extra step you mentioned is necessary. I moved on, but I want to share that I didn't uninstall the previous version before installing the new one, resulting in two versions installed. I tried uninstalling and reinstalling all versions as per the protocol, but it didn't resolve the issue

[David]

I'm wondering if the extra step you mentioned is necessary. I moved on, but I want to share that I didn't uninstall the previous version before installing the new one, resulting in two versions installed. I tried uninstalling and reinstalling all versions as per the protocol, but it didn't resolve the issue

[Kalavathi Nallathambi]

Hi David,

We have created a separate ticket under your account. Please follow the ticket for further updates. Therefore, we are marking this forum as solved.

Regards,

Kalavathi Nallathambi