System.Reflection.ReflectionTypeLoadException since the runner images version released on March 17, including .NET code sdk 10.0.201 and ASP.NET Core 10.0.5

[POFerro]

Hi,

Since the most recent update of runner images 17/03 my web apps built with these images stopped launching with exception:

System.Reflection.ReflectionTypeLoadException: Unable to load one or more of the requested types. Could not load file or assembly 'Typezor.Runtime, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'. 
The system cannot find the file specified. Could not load file or assembly 'Typezor.Runtime, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'. 
The system cannot find the file specified. at System.Reflection.RuntimeModule.GetDefinedTypes() at 
System.Reflection.RuntimeAssembly.get_DefinedTypes() at Microsoft.AspNetCore.Mvc.ApplicationParts.AssemblyPart.get_Types() at
Microsoft.AspNetCore.Mvc.Controllers.ControllerFeatureProvider.PopulateFeature(IEnumerable`1 parts, ControllerFeature feature) at 
Microsoft.AspNetCore.Mvc.ApplicationParts.ApplicationPartManager.PopulateFeature[TFeature](TFeature feature) at 
Microsoft.AspNetCore.Mvc.ApplicationModels.ControllerActionDescriptorProvider.GetControllerTypes() at 
Microsoft.AspNetCore.Mvc.ApplicationModels.ControllerActionDescriptorProvider.GetDescriptors() at 
Microsoft.AspNetCore.Mvc.ApplicationModels.ControllerActionDescriptorProvider.OnProvidersExecuting(ActionDescriptorProviderContext context) 
at Microsoft.AspNetCore.Mvc.Infrastructure.DefaultActionDescriptorCollectionProvider.UpdateCollection() at 
Microsoft.AspNetCore.Mvc.Infrastructure.DefaultActionDescriptorCollectionProvider.Initialize() at 
Microsoft.AspNetCore.Mvc.Infrastructure.DefaultActionDescriptorCollectionProvider.GetChangeToken() at 
Microsoft.Extensions.Primitives.ChangeToken.ChangeTokenRegistration`1..ctor(Func`1 changeTokenProducer, Action`1 changeTokenConsumer, 
TState state) at Microsoft.Extensions.Primitives.ChangeToken.OnChange(Func`1 changeTokenProducer, Action changeTokenConsumer) at 
Microsoft.AspNetCore.Mvc.Routing.ActionEndpointDataSourceBase.Subscribe() at 
Microsoft.AspNetCore.Mvc.Routing.ControllerActionEndpointDataSource..ctor(ControllerActionEndpointDataSourceIdProvider 
dataSourceIdProvider, IActionDescriptorCollectionProvider actions, ActionEndpointFactory endpointFactory, OrderedEndpointsSequenceProvider 
orderSequence) at Microsoft.AspNetCore.Builder.ControllerEndpointRouteBuilderExtensions.GetOrCreateDataSource(IEndpointRouteBuilder 
endpoints) at Microsoft.AspNetCore.Builder.ControllerEndpointRouteBuilderExtensions.MapControllers(IEndpointRouteBuilder endpoints) at 
Program.<Main>

Version Used:
.NET 10
ASP.NET Core ( tried any version from 10.0.2 to 10.0.5 )

Steps to Reproduce:

1. Create a basic web app with dependency to the nugets:

    <PackageReference Include="Typezor.SourceGenerator" Version="0.3.14" PrivateAssets="analyzer" />
    <PackageReference Include="Typezor.Runtime" Version="0.3.14" PrivateAssets="all" />
    <PackageReference Include="Typezor.CodeModel" Version="0.3.14" PrivateAssets="all" />

These are source generators that use cshtml files to generate code.
2. Include a basic cshtml that uses this source generator, like this:

@using System
@using System.IO
@using System.Linq
@using Typezor.CodeModel
@using File = System.IO.File
@inherits Typezor.TemplateBase<Typezor.CodeModel.File>
@{
    #region Model Classes
}

/****************************************************************************

  Generated by _models.cshtml - please don't make any changes in this file

****************************************************************************/


@{
@:declare namespace models {
@:
@:// #region Classes
@:
    foreach (var model in Model.Classes.Where(IsModelClass).OrderBy(c => c.FullName))
    {
@:  /** Generated from @(model.FullName) **/
@:  export interface @(model.Name)@(GenericTypes(model))@(model.BaseClass != null ? $" extends {model.BaseClass.Name}" : "") {
    }
@:
@:// #endregion Classes
@:
        Output.SaveAs(Path.Combine(Path.GetDirectoryName(TemplatePath), $"const.{model.Name}.ts"));
    }

    #endregion Model Classes
}

3. Reference the file in csproj like this:

  <ItemGroup>
    <None Remove="ClientApp\src\models\_models.cshtml" />
    <RazorGenerate Remove="ClientApp\src\models\_models.cshtml" />
    <Content Remove="ClientApp\src\models\_models.cshtml" />
  </ItemGroup>
  <ItemGroup>
    <AdditionalFiles Include="ClientApp\src\models\_models.cshtml" Typezor="true" />
  </ItemGroup>

4. Build the web site using the most recent runner images (windows-2022 or windows-2025-vs2026)
5. Publish to an Azure WebApp

Expected Behavior:
The web app should run, no Typezor libraries should be included or referenced by runtime code ( they are just source generator libraries, not for runtime )

Actual Behavior:
The site doesn't run throwing exception:
System.Reflection.ReflectionTypeLoadException: Unable to load one or more of the requested types. Could not load file or assembly 'Typezor.Runtime, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'

It's somehow thinking that there is this library to scan for Controller types when this dll was excluded from the build output

[JoeRobich]

@POFerro Did you mean to mark the Typezor package references with ExcludeAssets="all"

[POFerro]

Hi @JoeRobich ,

With that option it fails to compile saying that it doesn't recognize @inherits Typezor.TemplateBase<Typezor.CodeModel.File> when trying to run the source generator.
If you look ate the docs of the nuget itself these are the options they say should be used https://github.com/ReactiveThings/Typezor.

In the meanwhile I found a workaround which is to set <UseRazorSourceGenerator>false</UseRazorSourceGenerator> in the csproj, so it looks like in this new version it's still generating the cshtml code behind even with the files being removed like this

<ItemGroup>
    <None Remove="ClientApp\src\models\_models.cshtml" />
    <RazorGenerate Remove="ClientApp\src\models\_models.cshtml" />
    <Content Remove="ClientApp\src\models\_models.cshtml" />
  </ItemGroup>

Now I have to remove Razor generation completely for things to work.

[jjonescz]

Thanks for taking the time to report this issue. Unfortunately, it's unclear what the problem is here that represents a bug in the compiler.