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The reference assemblies for .NETFramework,Version=v5.0 were not found when using global Mono

See original GitHub issue

Hi Omnisharp team,

I have been developing a web api using dotnet 5. and when I launched the vscode this morning I realised the Intellisense stopped working even though I haven’t had any issues last night. I haven’t made any changes since then

Here is the log I get from Omnisharp

Starting OmniSharp server at 10/20/2020, 6:56:50 PM
    Target: /Users/aybarsacar/Desktop/cs/DatingApp/DatingApp.sln

OmniSharp server started with Mono 6.12.0.
    Path: /Users/aybarsacar/.vscode/extensions/ms-dotnettools.csharp-1.23.4/.omnisharp/1.37.3/omnisharp/OmniSharp.exe
    PID: 1586

[info]: OmniSharp.Stdio.Host
        Starting OmniSharp on MacOS 10.15.7 (x64)
[info]: OmniSharp.Services.DotNetCliService
        DotNetPath set to dotnet
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
        Located 2 MSBuild instance(s)
            1: Mono 16.8.0 - "/Library/Frameworks/Mono.framework/Versions/6.12.0/lib/mono/msbuild/Current/bin"
            2: StandAlone 16.8.0 - "/Users/aybarsacar/.vscode/extensions/ms-dotnettools.csharp-1.23.4/.omnisharp/1.37.3/omnisharp/.msbuild/Current/Bin"
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
        Registered MSBuild instance: Mono 16.8.0 - "/Library/Frameworks/Mono.framework/Versions/6.12.0/lib/mono/msbuild/Current/bin"
            CscToolExe = csc.exe
            CscToolPath = /Users/aybarsacar/.vscode/extensions/ms-dotnettools.csharp-1.23.4/.omnisharp/1.37.3/omnisharp/.msbuild/Current/Bin/Roslyn
[info]: OmniSharp.Cake.CakeProjectSystem
        Detecting Cake files in '/Users/aybarsacar/Desktop/cs/DatingApp'.
[info]: OmniSharp.Cake.CakeProjectSystem
        Could not find any Cake files
[info]: OmniSharp.MSBuild.ProjectSystem
        Detecting projects in '/Users/aybarsacar/Desktop/cs/DatingApp/DatingApp.sln'.
[info]: OmniSharp.MSBuild.ProjectManager
        Queue project update for '/Users/aybarsacar/Desktop/cs/DatingApp/API/API.csproj'
[info]: OmniSharp.Script.ScriptProjectSystem
        Detecting CSX files in '/Users/aybarsacar/Desktop/cs/DatingApp'.
[info]: OmniSharp.Script.ScriptProjectSystem
        Could not find any CSX files
[info]: OmniSharp.WorkspaceInitializer
        Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.CSharpFormattingWorkspaceOptionsProvider, Order: 0
[info]: OmniSharp.MSBuild.ProjectManager
        Loading project: /Users/aybarsacar/Desktop/cs/DatingApp/API/API.csproj
[info]: OmniSharp.WorkspaceInitializer
        Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.Completion.CompletionOptionsProvider, Order: 0
[info]: OmniSharp.WorkspaceInitializer
        Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.RenameWorkspaceOptionsProvider, Order: 100
[info]: OmniSharp.WorkspaceInitializer
        Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.ImplementTypeWorkspaceOptionsProvider, Order: 110
[info]: OmniSharp.WorkspaceInitializer
        Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.BlockStructureWorkspaceOptionsProvider, Order: 140
[info]: OmniSharp.WorkspaceInitializer
        Configuration finished.
[info]: OmniSharp.Stdio.Host
        Omnisharp server running using Stdio at location '/Users/aybarsacar/Desktop/cs/DatingApp' on host 1566.
[fail]: OmniSharp.MSBuild.ProjectLoader
        The reference assemblies for .NETFramework,Version=v5.0 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks
[warn]: OmniSharp.MSBuild.ProjectManager
        Failed to load project file '/Users/aybarsacar/Desktop/cs/DatingApp/API/API.csproj'.
/Users/aybarsacar/Desktop/cs/DatingApp/API/API.csproj
/Library/Frameworks/Mono.framework/Versions/6.12.0/lib/mono/msbuild/Current/bin/Microsoft.Common.CurrentVersion.targets(1193,5): Error: The reference assemblies for .NETFramework,Version=v5.0 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks

[fail]: OmniSharp.MSBuild.ProjectManager
        Attempted to update project that is not loaded: /Users/aybarsacar/Desktop/cs/DatingApp/API/API.csproj

here is my dotnet info:

.NET SDK (reflecting any global.json):
 Version:   5.0.100-rc.2.20479.15
 Commit:    da7dfa8840

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  10.15
 OS Platform: Darwin
 RID:         osx.10.15-x64
 Base Path:   /usr/local/share/dotnet/sdk/5.0.100-rc.2.20479.15/

Host (useful for support):
  Version: 5.0.0-rc.2.20475.5
  Commit:  c5a3f49c88

.NET SDKs installed:
  3.1.402 [/usr/local/share/dotnet/sdk]
  5.0.100-rc.2.20479.15 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 3.1.8 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0-rc.2.20475.17 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.22 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.8 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0-rc.2.20475.5 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

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

and my csproj file

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>net5.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Swashbuckle.AspNetCore" Version="5.5.1"/>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="5.0.0-rc.2.20475.6"/>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="5.0.0-rc.2.20475.6"/>
    <PackageReference Include="System.IdentityModel.Tokens.Jwt" Version="6.7.1"/>
    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="5.0.0-rc.2.20475.17"/>
    <PackageReference Include="AutoMapper.Extensions.Microsoft.DependencyInjection" Version="8.1.0"/>
    <PackageReference Include="CloudinaryDotNet" Version="1.11.0"/>
    <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="5.0.0-rc.2.20475.17"/>
  </ItemGroup>
</Project>

cheers!

Aybars

Issue Analytics

State:
Created 3 years ago
Reactions:7
Comments:8 (2 by maintainers)

Top GitHub Comments

7reactions

breitercommented, Oct 20, 2020

I’m having this same problem with the latest stable mono from the official package and the C# extension version 1.23.4 for VSCode and dotnet core 3.1 stable.

There are differences in the embedded version of mono 16.12.0.90. The msbuild version bundled in omnisharp is 16.8.0-preview-20475-05+aed5e7ed0.

Global mono

$ mono --version
Mono JIT compiler version 6.12.0.90 (2020-02/d3daacdaa80 Thu Jul 30 16:18:06 EDT 2020)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
	TLS:           
	SIGSEGV:       altstack
	Notification:  kqueue
	Architecture:  amd64
	Disabled:      none
	Misc:          softdebug 
	Interpreter:   yes
	LLVM:          yes(610)
	Suspend:       hybrid
	GC:            sgen (concurrent by default)
$ msbuild -version
Microsoft (R) Build Engine version 16.6.0 for Mono
Copyright (C) Microsoft Corporation. All rights reserved.

16.6.0.38001

 $ /Users/breiter/.vscode/extensions/ms-dotnettools.csharp-1.23.4/.omnisharp/1.37.3/bin/mono --version
Mono JIT compiler version 6.12.0.90 (2020-02/d3daacdaa80 Thu Jul 30 16:18:06 EDT 2020)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
	TLS:           
	SIGSEGV:       altstack
	Notification:  kqueue
	Architecture:  amd64
	Disabled:      none
	Misc:          softdebug 
	Interpreter:   yes
	LLVM:          yes(610)
	Suspend:       hybrid
	GC:            sgen (concurrent by default)

$ find /Users/breiter/.vscode/extensions/ms-dotnettools.csharp-1.23.4/.omnisharp/1.37.3/ -iname msbuild.dll
/Users/breiter/.vscode/extensions/ms-dotnettools.csharp-1.23.4/.omnisharp/1.37.3/omnisharp/.msbuild/Current/Bin/MSBuild.dll
/Users/breiter/.vscode/extensions/ms-dotnettools.csharp-1.23.4/.omnisharp/1.37.3/omnisharp/.msbuild/15.0/Bin/MSBuild.dll
$ mono /Users/breiter/.vscode/extensions/ms-dotnettools.csharp-1.23.4/.omnisharp/1.37.3/omnisharp/.msbuild/Current/Bin/MSBuild.dll -version
Microsoft (R) Build Engine version 16.8.0-preview-20475-05+aed5e7ed0 for Mono
Copyright (C) Microsoft Corporation. All rights reserved.

16.8.0.47505

Uninstalling the global mono or setting the UseGlobalMono option for vscode in settings.json to “never” resolves the problem.

{    
  "omnisharp.useGlobalMono": "never"
}

3reactions

filipwcommented, Oct 21, 2020

~~If you run into this issue please post the output of your mono -V command. If it is lower than Mono JIT compiler version 6.12.0.90, then make sure to download latest stable from here https://www.mono-project.com/download/stable/~~

~~Older Mono cannot handle .NET 5.0 RC2.~~

You can also tell OmniSharp to stop using global Mono by setting "omnisharp.useGlobalMono": "never" in the VS Code settings and restarting VS Code.

edit: we are still waiting for the updated Mono release here https://github.com/mono/mono/issues/20250

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