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The "CreateAppHost" task failed unexpectedly.

See original GitHub issue

Describe the bug

By using VS 2019 16.7.0 Preview 2 with dotnet-sdk-5.0.100-preview.7.20319.6-win-x64 installed, i cannot build any Asp.NetCore application! The build log has the following output:

1>FastUpToDate: Output 'C:\Users\RsZoli\source\repos\RFC7\RFC7\bin\Debug\net5.0\RFC7.pdb' does not exist, not up to date. (RFC7)
Restoring NuGet packages...
To prevent NuGet from restoring packages during build, open the Visual Studio Options dialog, click on the NuGet Package Manager node and uncheck 'Allow NuGet to download missing packages during build.'
Committing restore...
Assets file has not changed. Skipping assets file writing. Path: C:\Users\RsZoli\source\repos\RFC7\RFC7\obj\project.assets.json
Restored C:\Users\RsZoli\source\repos\RFC7\RFC7\RFC7.csproj (in 2 ms).
All projects are up-to-date for restore.
1>------ Build started: Project: RFC7, Configuration: Debug Any CPU ------
1>Build started 2020. 06. 21. 14:10:48.
1>Target _CheckForNETCoreSdkIsPreview:
1>    You are using a preview version of .NET. See: https://aka.ms/dotnet-core-preview
1>Target GenerateTargetFrameworkMonikerAttribute:
1>  Skipping target "GenerateTargetFrameworkMonikerAttribute" because all output files are up-to-date with respect to the input files.
1>Target CoreGenerateAssemblyInfo:
1>  Skipping target "CoreGenerateAssemblyInfo" because all output files are up-to-date with respect to the input files.
1>Target _DiscoverMvcApplicationParts:
1>    Creating "obj\Debug\net5.0\RFC7.MvcApplicationPartsAssemblyInfo.cache" because "AlwaysCreate" was specified.
1>Target _CoreGenerateRazorAssemblyInfo:
1>  Skipping target "_CoreGenerateRazorAssemblyInfo" because all output files are up-to-date with respect to the input files.
1>Target CoreCompile:
1>    Using shared compilation with compiler from directory: C:\Program Files (x86)\Microsoft Visual Studio\2019\Preview\MSBuild\Current\Bin\Roslyn
1>Target _CreateAppHost:
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: The "CreateAppHost" task failed unexpectedly.
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: System.IO.FileLoadException: Could not load file or assembly 'System.Runtime.CompilerServices.Unsafe, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. Strong name validation failed. (Exception from HRESULT: 0x8013141A)
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: File name: 'System.Runtime.CompilerServices.Unsafe, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' ---> System.Security.SecurityException: Strong name validation failed. (Exception from HRESULT: 0x8013141A)
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: The Zone of the assembly that failed was:
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: MyComputer
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.MachOUtils.RemoveSignature(String filePath)
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.HostWriter.<>c__DisplayClass2_0.<CreateAppHost>g__RemoveSignatureIfMachO|2()
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.HostModel.RetryUtil.RetryOnIOError(Action func)
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.HostWriter.CreateAppHost(String appHostSourceFilePath, String appHostDestinationFilePath, String appBinaryFilePath, Boolean windowsGraphicalUserInterface, String assemblyToCopyResorcesFrom)
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.Build.Tasks.CreateAppHost.ExecuteCore()
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.Build.Tasks.TaskBase.Execute()
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: 
1>    C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:
1>Done building target "_CreateAppHost" in project "RFC7.csproj" -- FAILED.
1>
1>Done building project "RFC7.csproj" -- FAILED.
1>
1>Build FAILED.
1>
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: The "CreateAppHost" task failed unexpectedly.
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: System.IO.FileLoadException: Could not load file or assembly 'System.Runtime.CompilerServices.Unsafe, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. Strong name validation failed. (Exception from HRESULT: 0x8013141A)
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: File name: 'System.Runtime.CompilerServices.Unsafe, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' ---> System.Security.SecurityException: Strong name validation failed. (Exception from HRESULT: 0x8013141A)
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: The Zone of the assembly that failed was:
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: MyComputer
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.MachOUtils.RemoveSignature(String filePath)
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.HostWriter.<>c__DisplayClass2_0.<CreateAppHost>g__RemoveSignatureIfMachO|2()
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.HostModel.RetryUtil.RetryOnIOError(Action func)
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.HostWriter.CreateAppHost(String appHostSourceFilePath, String appHostDestinationFilePath, String appBinaryFilePath, Boolean windowsGraphicalUserInterface, String assemblyToCopyResorcesFrom)
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.Build.Tasks.CreateAppHost.ExecuteCore()
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.NET.Build.Tasks.TaskBase.Execute()
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018:    at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: 
1>C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(428,5): error MSB4018: 
1>    0 Warning(s)
1>    1 Error(s)
1>
1>Time Elapsed 00:00:51.86
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

However, building the very same project from command line, it builds just fine:

Microsoft (R) Build Engine version 16.7.0-preview-20310-07+ee1c9fd0c for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  Restored c:\Users\RsZoli\source\repos\RFC7\RFC7\RFC7.csproj (in 194 ms).
  You are using a preview version of .NET. See: https://aka.ms/dotnet-core-preview
  RFC7 -> c:\Users\RsZoli\source\repos\RFC7\RFC7\bin\Debug\net5.0\RFC7.dll
  RFC7 -> c:\Users\RsZoli\source\repos\RFC7\RFC7\bin\Debug\net5.0\RFC7.Views.dll

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:03.40

To Reproduce

Install VS 2019 16.7.0 Preview 2 and the dotnet-sdk-5.0.100-preview.7.20319.6-win-x64, create a new web application and build said application.

Exceptions (if any)

n/a

Further technical details

ASP.NET Core version: dotnet-sdk-5.0.100-preview.7.20319.6-win-x64

.NET SDK (reflecting any global.json):
 Version:   5.0.100-preview.7.20319.6
 Commit:    3c6656f83b

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.18363
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\5.0.100-preview.7.20319.6\

Host (useful for support):
  Version: 5.0.0-preview.7.20318.2
  Commit:  38192e3cbd

.NET SDKs installed:
  3.1.301 [C:\Program Files\dotnet\sdk]
  3.1.400-preview-015151 [C:\Program Files\dotnet\sdk]
  3.1.400-preview-015186 [C:\Program Files\dotnet\sdk]
  5.0.100-preview.7.20319.6 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.19 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.19 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0-preview.7.20311.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.19 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0-preview.7.20318.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0-preview.7.20311.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET runtimes or SDKs:
  https://aka.ms/dotnet-download