ASP NET Core 2 Cannot find compilation library location for package 'Projectname.Model'

Question

In my solution, I have two projects. One of them is web project and the other one is Model project. You can see my solution structure in below:

Now when I run application I get the following error:

InvalidOperationException: Cannot find compilation library location for package 'ContosoUniversity.Model'

And here is full stack trace :

An unhandled exception occurred while processing the request.
InvalidOperationException: Cannot find compilation library location for package 'ContosoUniversity.Model'
Microsoft.Extensions.DependencyModel.CompilationLibrary.ResolveReferencePaths(ICompilationAssemblyResolver resolver, List<string> assemblies)
InvalidOperationException: Cannot find compilation library location for package 'ContosoUniversity.Model'
Microsoft.Extensions.DependencyModel.CompilationLibrary.ResolveReferencePaths(ICompilationAssemblyResolver resolver, List<string> assemblies)
Microsoft.Extensions.DependencyModel.CompilationLibrary.ResolveReferencePaths()
Microsoft.AspNetCore.Mvc.ApplicationParts.AssemblyPart+<>c.<GetReferencePaths>b__8_0(CompilationLibrary library)
System.Linq.Enumerable+SelectManySingleSelectorIterator.MoveNext()
Microsoft.AspNetCore.Mvc.Razor.Compilation.MetadataReferenceFeatureProvider.PopulateFeature(IEnumerable<ApplicationPart> parts, MetadataReferenceFeature feature)
Microsoft.AspNetCore.Mvc.ApplicationParts.ApplicationPartManager.PopulateFeature<TFeature>(TFeature feature)
Microsoft.AspNetCore.Mvc.Razor.Internal.DefaultRazorReferenceManager.GetCompilationReferences()
System.Threading.LazyInitializer.EnsureInitializedCore<T>(ref T target, ref bool initialized, ref object syncLock, Func<T> valueFactory)
Microsoft.AspNetCore.Mvc.Razor.Internal.DefaultRazorReferenceManager.get_CompilationReferences()
Microsoft.AspNetCore.Mvc.Razor.Internal.LazyMetadataReferenceFeature.get_References()
Microsoft.CodeAnalysis.Razor.CompilationTagHelperFeature.GetDescriptors()
Microsoft.AspNetCore.Razor.Language.DefaultRazorTagHelperBinderPhase.ExecuteCore(RazorCodeDocument codeDocument)
Microsoft.AspNetCore.Razor.Language.RazorEnginePhaseBase.Execute(RazorCodeDocument codeDocument)
Microsoft.AspNetCore.Razor.Language.DefaultRazorEngine.Process(RazorCodeDocument document)
Microsoft.AspNetCore.Razor.Language.RazorTemplateEngine.GenerateCode(RazorCodeDocument codeDocument)
Microsoft.AspNetCore.Mvc.Razor.Internal.RazorViewCompiler.CompileAndEmit(string relativePath)
Microsoft.AspNetCore.Mvc.Razor.Internal.RazorViewCompiler.CreateCacheEntry(string normalizedPath) 
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
System.Runtime.CompilerServices.TaskAwaiter.GetResult()
Microsoft.AspNetCore.Mvc.Razor.Internal.DefaultRazorPageFactoryProvider.CreateFactory(string relativePath)
Microsoft.AspNetCore.Mvc.Razor.RazorViewEngine.CreateCacheResult(HashSet<IChangeToken> expirationTokens, string relativePath, bool isMainPage)
Microsoft.AspNetCore.Mvc.Razor.RazorViewEngine.OnCacheMiss(ViewLocationExpanderContext expanderContext, ViewLocationCacheKey cacheKey)
Microsoft.AspNetCore.Mvc.Razor.RazorViewEngine.LocatePageFromViewLocations(ActionContext actionContext, string pageName, bool isMainPage)
Microsoft.AspNetCore.Mvc.Razor.RazorViewEngine.FindView(ActionContext context, string viewName, bool isMainPage)
Microsoft.AspNetCore.Mvc.ViewEngines.CompositeViewEngine.FindView(ActionContext context, string viewName, bool isMainPage)
Microsoft.AspNetCore.Mvc.ViewFeatures.Internal.ViewResultExecutor.FindView(ActionContext actionContext, ViewResult viewResult)
Microsoft.AspNetCore.Mvc.ViewResult+<ExecuteResultAsync>d__26.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker+<InvokeResultAsync>d__19.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker+<InvokeNextResultFilterAsync>d__24.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResultExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker+<InvokeNextResourceFilter>d__22.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker+<InvokeFilterPipelineAsync>d__17.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker+<InvokeAsync>d__15.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Builder.RouterMiddleware+<Invoke>d__4.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware+<Invoke>d__7.MoveNext()

I use ASP NET Core 2 and VS17.

Here is my ContosoUniversity.csproj file if you need it:

<Project Sdk="Microsoft.NET.Sdk.Web">

<PropertyGroup>
  <TargetFramework>netcoreapp2.0</TargetFramework>
</PropertyGroup>

<ItemGroup>
  <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.0" />
  <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.0.0" />
</ItemGroup>

<ItemGroup>
  <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.0" />
</ItemGroup>

<ItemGroup>
  <Reference Include="ContosoUniversity.Model">
    <HintPath>..\ContosoUniversity.Model\bin\Debug\netcoreapp2.0\ContosoUniversity.Model.dll</HintPath>
  </Reference>
</ItemGroup>

</Project>

What should I do to solve this problem?

Answer 1

It's likely that you are publishing the app without reference assemblies. Try setting

<CopyRefAssembliesToPublishDirectory>true</CopyRefAssembliesToPublishDirectory>

in your app's project file.

Answer 2

If your app is compiling Razor code in runtime and you are in .netcore2+ it seems you need to add this to your project:

<MvcRazorExcludeRefAssembliesFromPublish>false</MvcRazorExcludeRefAssembliesFromPublish>

This copies the refs folder on publish - it is large - but it seems to be needed