RazorLight Could not load file or assembly System.Threading.AccessControl

The goal is to generate HTML from a .cshtml file

When using RazorLight I get the following error:

 System.IO.FileNotFoundException: Could not load file or assembly 'System.Threading.AccessControl, Version=4.0.5.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
File name: 'System.Threading.AccessControl, Version=4.0.5.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' at System.Reflection.RuntimeAssembly.nLoad(AssemblyName fileName, String codeBase, RuntimeAssembly assemblyContext, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, AssemblyLoadContext assemblyLoadContext) at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, StackCrawlMark& stackMark, AssemblyLoadContext assemblyLoadContext) at System.Reflection.Assembly.Load(AssemblyName assemblyRef, StackCrawlMark& stackMark, AssemblyLoadContext assemblyLoadContext) at System.Reflection.Assembly.Load(AssemblyName assemblyRef) at RazorLight.Compilation.DefaultMetadataReferenceManager.GetReferencedAssemblies(Assembly a, IEnumerable`1 excludedAssemblies, HashSet`1 visitedAssemblies)+MoveNext() at RazorLight.Compilation.DefaultMetadataReferenceManager.GetReferencedAssemblies(Assembly a, IEnumerable`1 excludedAssemblies, HashSet`1 visitedAssemblies)+MoveNext() at RazorLight.Compilation.DefaultMetadataReferenceManager.GetReferencedAssemblies(Assembly a, IEnumerable`1 excludedAssemblies, HashSet`1 visitedAssemblies)+MoveNext() at System.Linq.Set`1.UnionWith(IEnumerable`1 other) at System.Linq.Enumerable.UnionIterator`1.FillSet() at System.Linq.Enumerable.UnionIterator`1.ToArray() at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source) at RazorLight.Compilation.DefaultMetadataReferenceManager.Resolve(Assembly assembly, DependencyContext dependencyContext) at RazorLight.Compilation.DefaultMetadataReferenceManager.Resolve(Assembly assembly) at RazorLight.Compilation.RoslynCompilationService.EnsureOptions() at RazorLight.Compilation.RoslynCompilationService.get_ParseOptions() at RazorLight.Compilation.RoslynCompilationService.CreateSyntaxTree(SourceText sourceText) at RazorLight.Compilation.RoslynCompilationService.CreateCompilation(String compilationContent, String assemblyName) at RazorLight.Compilation.RoslynCompilationService.CompileAndEmit(IGeneratedRazorTemplate razorTemplate) at RazorLight.Compilation.RazorTemplateCompiler.CompileAndEmit(RazorLightProjectItem projectItem) at RazorLight.Compilation.RazorTemplateCompiler.OnCacheMissAsync(String templateKey)

I installed the NuGet package RazorLight 2.0.0-rc.3 and this is my code to generate html from a .cshtml file:

private async Task<string> RenderRazorTemplate(string key, Type viewModelType, object viewModel)
{ var engine = new RazorLightEngineBuilder() .UseEmbeddedResourcesProject(Assembly.GetExecutingAssembly()) // Use the Executing Assembly as project that embeds the .cshtml templates .SetOperatingAssembly(viewModelType.Assembly) // Without this, you'll get a Exception saying that the Assembly can't find the AntiForgery.dll .UseMemoryCachingProvider() .Build(); return await engine.CompileRenderAsync(key, viewModel);
}

Trying to add the System.Threading.AccessControl NuGet Package, but then another file or assembly can't be loaded (so never ending story of adding packages). There must be another solution.

I am using .NET Core 3.1.

1 Answer

For me the issue was that the Engine was used in a IRequestHandler from Mediatr.

Outsourcing the engine to the controller instead of having it inside the IRequestHandler fixed the issue.