Baixei o zip da aula seguinte(Aula 3), para tentar comparar e achar onde poderia estar o erro, mas o arquivo nem compilou. Segue a mensagem de erro que aparece na página do Google.
[DirectoryNotFoundException: Não foi possível localizar uma parte do caminho 'C:\Users\sergi_000\Downloads\aspnet-identity-parte-1-aula-02\aspnet-identity-parte-1-aula-02\src\ByteBank.Forum\bin\roslyn\csc.exe'.]
System.IO._Error.WinIOError(Int32 errorCode, String maybeFullPath) +373
System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITYATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost) +738
System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share) +68
Microsoft.CodeDom.Providers.DotNetCompilerPlatform.Compiler.get_CompilerName() +91
Microsoft.CodeDom.Providers.DotNetCompilerPlatform.Compiler.FromFileBatch(CompilerParameters options, String[] fileNames) +658
Microsoft.CodeDom.Providers.DotNetCompilerPlatform.Compiler.CompileAssemblyFromFileBatch(CompilerParameters options, String[] fileNames) +186
System.CodeDom.Compiler.CodeDomProvider.CompileAssemblyFromFile(CompilerParameters options, String[] fileNames) +25
System.Web.Compilation.AssemblyBuilder.Compile() +941
System.Web.Compilation.BuildProvidersCompiler.PerformBuild() +306
System.Web.Compilation.ApplicationBuildProvider.GetGlobalAsaxBuildResult(Boolean isPrecompiledApp) +272
System.Web.Compilation.BuildManager.CompileGlobalAsax() +44
System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +312
[HttpException (0x80004005): Não foi possível localizar uma parte do caminho 'C:\Users\sergi_000\Downloads\aspnet-identity-parte-1-aula-02\aspnet-identity-parte-1-aula-02\src\ByteBank.Forum\bin\roslyn\csc.exe'.]
System.Web.Compilation.BuildManager.ReportTopLevelCompilationException() +63
System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +437
System.Web.Compilation.BuildManager.CallAppInitializeMethod() +31
System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +707
[HttpException (0x80004005): Não foi possível localizar uma parte do caminho 'C:\Users\sergi_000\Downloads\aspnet-identity-parte-1-aula-02\aspnet-identity-parte-1-aula-02\src\ByteBank.Forum\bin\roslyn\csc.exe'.]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +660
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +89
System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +188