Skip to main content

Troubleshooting

The two problems that most often stop a new installation are Visual Studio not listing the Wisej.NET project templates, and the designer failing to open a page. Both are covered here, for Visual Studio 2022 and Visual Studio 2026. License problems are on the License Activation page.

Missing Templates​

The Wisej.NET project templates and item templates are installed by the Wisej.NET for Visual Studio extension — the VSIX downloaded from wisej.com/builds — not by the Wisej-4 NuGet package. If the Create a new project dialog lists no Wisej.NET templates after installing it, work through the steps below in order.

danger

The templates never show up in a Visual Studio Experimental Instance. Make sure you are running the regular instance.

Refresh the Visual Studio configuration​

Close every instance of Visual Studio, open the Developer Command Prompt of the Visual Studio you installed the extension into, and run:

devenv /updateConfiguration

This makes Visual Studio rebuild the configuration it caches for its extensions and templates. Start Visual Studio again and open the Create a new project dialog.

Check the extension folder​

Since Wisej.NET 3.0 the designer and the templates are distributed as a Visual Studio extension, which Visual Studio unpacks into a per-user folder:

%LOCALAPPDATA%\Microsoft\VisualStudio\{version}_{instance}\Extensions\{extension}

Every part of that name differs from one machine to another. {version} is 17.0 for Visual Studio 2022 and 18.0 for Visual Studio 2026; {instance} is the id of that Visual Studio installation (ignore the folders ending in Exp, which belong to the Experimental Instance); and {extension} is a random name Visual Studio picks for each extension — the one that belongs to Wisej.NET is the folder whose extension.vsixmanifest names Wisej.NET. For example:

%LOCALAPPDATA%\Microsoft\VisualStudio\17.0_315d49d1\Extensions\x2rkvlci.xbt

Start with dir %LOCALAPPDATA%\Microsoft\VisualStudio to see which installations there are. Each Visual Studio has an Extensions folder of its own, so an extension installed into Visual Studio 2022 is not available in Visual Studio 2026: the VSIX installer lists the Visual Studio installations it can install into, and the one you use has to be ticked.

Download the extension​

If the folder is missing, or the templates inside it are, install the extension again: run the .vsix file you installed from and choose Repair, or download the current Wisej.NET for Visual Studio build from wisej.com/builds and install it over the existing one — the steps are in Getting Started. Then run devenv /updateConfiguration again.

Wisej.NET is no longer published on the Visual Studio Marketplace, so the Extension Manager neither finds nor updates it. wisej.com/builds is the only place the extension comes from, for the current release as well as for earlier ones.

Shared development machines

A VSIX installs into the profile of the user who runs it. On a machine shared by several developers, install it for all users instead, from an elevated Developer Command Prompt:

VSIXInstaller /admin "path\to\the\downloaded.vsix"

The extension is then deployed machine-wide rather than into one user profile.

Clear the templates cache​

If the extension is installed and the templates are still not listed, delete Visual Studio's template caches and let it rebuild them. They are two folders inside the installation's folder under %LOCALAPPDATA%\Microsoft\VisualStudio — the one whose name starts with 17.0_ for Visual Studio 2022 and 18.0_ for Visual Studio 2026, without the Exp suffix. Close Visual Studio, then:

dir %LOCALAPPDATA%\Microsoft\VisualStudio
rd /s /q %LOCALAPPDATA%\Microsoft\VisualStudio\{version}_{instance}\ItemTemplatesCache_{00000000-0000-0000-0000-000000000000}
rd /s /q %LOCALAPPDATA%\Microsoft\VisualStudio\{version}_{instance}\ProjectTemplatesCache_{00000000-0000-0000-0000-000000000000}

Run devenv /updateConfiguration again and start Visual Studio.

Designer Error​

Errors can occur when you open a page or a window in the designer. The most common one, "Unable to cast object of type…", comes from Visual Studio loading shadow copies of the assemblies the designer uses.

Assemblies cannot be unloaded in .NET Framework, so Visual Studio loads shadow copies of the ones the designer needs. Sometimes it ends up loading the same assembly more than once — typically after opening pages from two projects that reference different versions of Wisej.NET in one Visual Studio instance — and the same type then exists twice, which is what the "Unable to cast" error reports. Clean and Rebuild below fixes it in most cases; if not, clear the designer assembly cache.

Two designers

Wisej.NET 4 has two designers. The one for the .NET Framework target runs inside Visual Studio; the one for .NET Core runs in a separate DesignToolsServer.exe process. The shadow-copy problem above is the .NET Framework designer's; with the .NET Core designer, the Recycle button in the designer's diagnostic window restarts the DesignToolsServer.exe process instead. See .NET Core Designer.

Rendering engine​

The designer draws the design surface with an embedded browser: Edge/Chrome (the WebView2 runtime) by default, or the legacy Internet Explorer engine where it is still offered. Microsoft updates WebView2 automatically, and an update can affect the Edge-based renderer. If the designer opens with an empty surface, or stops rendering after a Windows update, WebView2 is the likely cause:

  1. Click the browser icon at the right end of the toolbar at the bottom of the designer, next to the license icon. It opens the Designer Options dialog, which shows the engine in use and its version number.
  2. Report the problem on the support forum, including that version number. Designer builds that fix such problems are published on wisej.com/builds.
  3. Meanwhile, switching to the Internet Explorer engine in the same dialog can work around it. Some complex JavaScript components do not render with that engine.

The Designer Options dialog, with the IE and Edge/Chrome engines and the version number of the one in use

The Designer Options dialog. The version is shown next to the Edge/Chrome option; the other settings are described under Rendering Options.

Clean and Rebuild​

These steps resolve most assembly-loading problems:

  1. Close all designer tabs.
  2. Close all instances of Visual Studio.
  3. Delete the bin, obj and .vs folders of the solution.
  4. Open Visual Studio and reload the solution.
  5. Rebuild the solution, then open the designer again.

If the error persists, clear the designer assembly cache and repeat these steps.

Clear Designer Assembly Cache​

Visual Studio keeps the shadow copies of the assemblies loaded by the designer here:

%LOCALAPPDATA%\Microsoft\VisualStudio\{version}_{instance}\Designer\ShadowCache

As above, {version}_{instance} is the folder of your Visual Studio installation — 17.0_… for Visual Studio 2022, 18.0_… for Visual Studio 2026. Close Visual Studio, delete the folder, and let Visual Studio recreate it:

dir %LOCALAPPDATA%\Microsoft\VisualStudio
rd /s /q %LOCALAPPDATA%\Microsoft\VisualStudio\{version}_{instance}\Designer\ShadowCache

Open Visual Studio, rebuild the solution and check whether the designer loads.