Omnisharp-roslyn: Snap-installed .NET Core breaks VS Code

[bradwilson]

If you install .NET Core via Snap package, Omnisharp does not find it and will not use it.

Pre-Requisites

These instructions are given from the perspective of Ubuntu 18.04 using bash as the shell, but likely fail for any Linux-based OS.

1. Install .NET Core via snap:
   sudo snap install --classic dotnet-sdk
2. Create a shortcut so dotnet points to the Snap installation:
   sudo ln -s /snap/bin/dotnet-sdk.dotnet /snap/bin/dotnet
3. Ensure /snap/bin is in your PATH:
   export PATH=$PATH:/snap/bin
4. Ensure that DOTNET_ROOT is set appropriate:
   export DOTNET_ROOT=/snap/dotnet-sdk/current

Reproduction

Create a .NET Core project, and open it with VS Code w/ C#/Omnisharp extension installed:

$ dotnet new classlib -o sample
The template "Class library" was created successfully.

Processing post-creation actions...
Running 'dotnet restore' on sample/sample.csproj...
  Restore completed in 1.15 sec for /home/user/sample/sample.csproj.

Restore succeeded.

$ code sample

Expected behavior

Project opens and is usable with VS Code.

Actual behavior

Omnisharp displays an error message:

Some projects have trouble loading.

The output window "Omnisharp Log" tab shows the following error:

/home/user/sample/sample.csproj(1,1)
Microsoft.Build.Exceptions.InvalidProjectFileException: The SDK 'Microsoft.NET.Sdk' specified could not be found.

Full log follows:

Starting OmniSharp server at 5/13/2019, 12:19:51 PM
    Target: /home/user/sample

OmniSharp server started.
    Path: /home/user/.vscode/extensions/ms-vscode.csharp-1.19.1/.omnisharp/1.32.19/run
    PID: 7824

[info]: OmniSharp.Stdio.Host
        Starting OmniSharp on ubuntu 18.4 (x64)
[info]: OmniSharp.Services.DotNetCliService
        DotNetPath set to dotnet
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
        Located 1 MSBuild instance(s)
            1: StandAlone 15.0 - "/home/user/.vscode/extensions/ms-vscode.csharp-1.19.1/.omnisharp/1.32.19/omnisharp/.msbuild/Current/Bin"
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
        MSBUILD_EXE_PATH environment variable set to '/home/user/.vscode/extensions/ms-vscode.csharp-1.19.1/.omnisharp/1.32.19/omnisharp/.msbuild/Current/Bin/MSBuild.dll'
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
        Registered MSBuild instance: StandAlone 15.0 - "/home/user/.vscode/extensions/ms-vscode.csharp-1.19.1/.omnisharp/1.32.19/omnisharp/.msbuild/Current/Bin"
            MSBuildExtensionsPath = /home/user/.vscode/extensions/ms-vscode.csharp-1.19.1/.omnisharp/1.32.19/omnisharp/.msbuild
            BypassFrameworkInstallChecks = true
            CscToolPath = /home/user/.vscode/extensions/ms-vscode.csharp-1.19.1/.omnisharp/1.32.19/omnisharp/.msbuild/Current/Bin/Roslyn
            CscToolExe = csc.exe
            MSBuildToolsPath = /home/user/.vscode/extensions/ms-vscode.csharp-1.19.1/.omnisharp/1.32.19/omnisharp/.msbuild/Current/Bin
[info]: OmniSharp.Cake.CakeProjectSystem
        Detecting Cake files in '/home/user/sample'.
[info]: OmniSharp.Cake.CakeProjectSystem
        Could not find any Cake files
[info]: OmniSharp.WorkspaceInitializer
        Project system 'OmniSharp.DotNet.DotNetProjectSystem' is disabled in the configuration.
[info]: OmniSharp.MSBuild.ProjectSystem
        No solution files found in '/home/user/sample'
[info]: OmniSharp.MSBuild.ProjectManager
        Queue project update for '/home/user/sample/sample.csproj'
[info]: OmniSharp.Script.ScriptProjectSystem
        Detecting CSX files in '/home/user/sample'.
[info]: OmniSharp.Script.ScriptProjectSystem
        Could not find any CSX files
[info]: OmniSharp.WorkspaceInitializer
        Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.CSharpWorkspaceOptionsProvider
[info]: OmniSharp.MSBuild.ProjectManager
        Loading project: /home/user/sample/sample.csproj
[info]: OmniSharp.WorkspaceInitializer
        Configuration finished.
[info]: OmniSharp.Stdio.Host
        Omnisharp server running using Stdio at location '/home/user/sample' on host 7482.
[warn]: OmniSharp.MSBuild.ProjectManager
        Failed to load project file '/home/user/sample/sample.csproj'.
/home/user/sample/sample.csproj(1,1)
Microsoft.Build.Exceptions.InvalidProjectFileException: The SDK 'Microsoft.NET.Sdk' specified could not be found.  /home/user/sample/sample.csproj
  at Microsoft.Build.Shared.ProjectErrorUtilities.ThrowInvalidProject (System.String errorSubCategoryResourceName, Microsoft.Build.Shared.IElementLocation elementLocation, System.String resourceName, System.Object[] args) [0x00040] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Shared.ProjectErrorUtilities.VerifyThrowInvalidProject[T1] (System.Boolean condition, System.String errorSubCategoryResourceName, Microsoft.Build.Shared.IElementLocation elementLocation, System.String resourceName, T1 arg0) [0x00003] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Shared.ProjectErrorUtilities.ThrowInvalidProject[T1] (Microsoft.Build.Shared.IElementLocation elementLocation, System.String resourceName, T1 arg0) [0x00000] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Evaluator`4[P,I,M,D].ExpandAndLoadImportsFromUnescapedImportExpressionConditioned (System.String directoryOfImportingFile, Microsoft.Build.Construction.ProjectImportElement importElement, System.Collections.Generic.List`1[Microsoft.Build.Construction.ProjectRootElement]& projects, Microsoft.Build.BackEnd.SdkResolution.SdkResult& sdkResult, System.Boolean throwOnFileNotExistsError) [0x0024e] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Evaluator`4[P,I,M,D].ExpandAndLoadImports (System.String directoryOfImportingFile, Microsoft.Build.Construction.ProjectImportElement importElement, Microsoft.Build.BackEnd.SdkResolution.SdkResult& sdkResult) [0x00027] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Evaluator`4[P,I,M,D].EvaluateImportElement (System.String directoryOfImportingFile, Microsoft.Build.Construction.ProjectImportElement importElement) [0x0000d] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Evaluator`4[P,I,M,D].PerformDepthFirstPass (Microsoft.Build.Construction.ProjectRootElement currentProjectOrImport) [0x000e6] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Evaluator`4[P,I,M,D].Evaluate (Microsoft.Build.BackEnd.Logging.ILoggingService loggingService, Microsoft.Build.Framework.BuildEventContext buildEventContext) [0x00103] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Evaluator`4[P,I,M,D].Evaluate (Microsoft.Build.Evaluation.IEvaluatorData`4[P,I,M,D] data, Microsoft.Build.Construction.ProjectRootElement root, Microsoft.Build.Evaluation.ProjectLoadSettings loadSettings, System.Int32 maxNodeCount, Microsoft.Build.Collections.PropertyDictionary`1[T] environmentProperties, Microsoft.Build.BackEnd.Logging.ILoggingService loggingService, Microsoft.Build.Evaluation.IItemFactory`2[S,T] itemFactory, Microsoft.Build.Evaluation.IToolsetProvider toolsetProvider, Microsoft.Build.Evaluation.ProjectRootElementCache projectRootElementCache, Microsoft.Build.Framework.BuildEventContext buildEventContext, Microsoft.Build.BackEnd.SdkResolution.ISdkResolverService sdkResolverService, System.Int32 submissionId, Microsoft.Build.Evaluation.Context.EvaluationContext evaluationContext) [0x0002d] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Project.Reevaluate (Microsoft.Build.BackEnd.Logging.ILoggingService loggingServiceForEvaluation, Microsoft.Build.Evaluation.ProjectLoadSettings loadSettings, Microsoft.Build.Evaluation.Context.EvaluationContext evaluationContext) [0x0005e] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Project.ReevaluateIfNecessary (Microsoft.Build.BackEnd.Logging.ILoggingService loggingServiceForEvaluation, Microsoft.Build.Evaluation.ProjectLoadSettings loadSettings, Microsoft.Build.Evaluation.Context.EvaluationContext evaluationContext) [0x00035] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Project.ReevaluateIfNecessary (Microsoft.Build.BackEnd.Logging.ILoggingService loggingServiceForEvaluation, Microsoft.Build.Evaluation.Context.EvaluationContext evaluationContext) [0x00000] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Project.ReevaluateIfNecessary (Microsoft.Build.Evaluation.Context.EvaluationContext evaluationContext) [0x00007] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Project.Initialize (System.Collections.Generic.IDictionary`2[TKey,TValue] globalProperties, System.String toolsVersion, System.String subToolsetVersion, Microsoft.Build.Evaluation.ProjectLoadSettings loadSettings, Microsoft.Build.Evaluation.Context.EvaluationContext evaluationContext) [0x00126] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Project..ctor (System.String projectFile, System.Collections.Generic.IDictionary`2[TKey,TValue] globalProperties, System.String toolsVersion, System.String subToolsetVersion, Microsoft.Build.Evaluation.ProjectCollection projectCollection, Microsoft.Build.Evaluation.ProjectLoadSettings loadSettings, Microsoft.Build.Evaluation.Context.EvaluationContext evaluationContext) [0x00093] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Project..ctor (System.String projectFile, System.Collections.Generic.IDictionary`2[TKey,TValue] globalProperties, System.String toolsVersion, System.String subToolsetVersion, Microsoft.Build.Evaluation.ProjectCollection projectCollection, Microsoft.Build.Evaluation.ProjectLoadSettings loadSettings) [0x00000] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Project..ctor (System.String projectFile, System.Collections.Generic.IDictionary`2[TKey,TValue] globalProperties, System.String toolsVersion, Microsoft.Build.Evaluation.ProjectCollection projectCollection, Microsoft.Build.Evaluation.ProjectLoadSettings loadSettings) [0x00000] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.Project..ctor (System.String projectFile, System.Collections.Generic.IDictionary`2[TKey,TValue] globalProperties, System.String toolsVersion, Microsoft.Build.Evaluation.ProjectCollection projectCollection) [0x00000] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.ProjectCollection.LoadProject (System.String fileName, System.Collections.Generic.IDictionary`2[TKey,TValue] globalProperties, System.String toolsVersion) [0x000f7] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at Microsoft.Build.Evaluation.ProjectCollection.LoadProject (System.String fileName, System.String toolsVersion) [0x00000] in <4e0a1f1d78cf4c1ebd6f9a3dbcebf3bb>:0 
  at OmniSharp.MSBuild.ProjectLoader.EvaluateProjectFileCore (System.String filePath) [0x0003f] in <69148e098afe4042aa56606d5bafd188>:0 
  at OmniSharp.MSBuild.ProjectLoader.BuildProject (System.String filePath) [0x0000d] in <69148e098afe4042aa56606d5bafd188>:0 
  at OmniSharp.MSBuild.ProjectFile.ProjectFileInfo.Load (System.String filePath, OmniSharp.MSBuild.ProjectIdInfo projectIdInfo, OmniSharp.MSBuild.ProjectLoader loader) [0x00015] in <69148e098afe4042aa56606d5bafd188>:0 
  at OmniSharp.MSBuild.ProjectManager+<>c__DisplayClass30_0.<LoadProject>b__0 () [0x00000] in <69148e098afe4042aa56606d5bafd188>:0 
  at (wrapper delegate-invoke) System.Func`1[System.ValueTuple`3[OmniSharp.MSBuild.ProjectFile.ProjectFileInfo,System.Collections.Immutable.ImmutableArray`1[OmniSharp.MSBuild.Logging.MSBuildDiagnostic],OmniSharp.MSBuild.Notification.ProjectLoadedEventArgs]].invoke_TResult()
  at OmniSharp.MSBuild.ProjectManager.LoadOrReloadProject (System.String projectFilePath, System.Func`1[TResult] loader) [0x0001b] in <69148e098afe4042aa56606d5bafd188>:0 

[fail]: OmniSharp.MSBuild.ProjectManager
        Attempted to update project that is not loaded: /home/user/sample/sample.csproj

[grantzvolsky]

Here's a quick fix that worked for me. Add the file below to your /etc/profile.d:

/etc/profile.d/04-fix-dotnet.sh:

#!/bin/bash
export DOTNET_ROOT=/snap/dotnet-sdk/current
export MSBuildSDKsPath=$DOTNET_ROOT/sdk/$(${DOTNET_ROOT}/dotnet --version)/Sdks
export PATH="${PATH}:${DOTNET_ROOT}"

export PATH="$PATH:$HOME/.dotnet/tools"

In your particular case it seems to be the MSBuildSDKsPath variable that is not configured.

[wegel]

@grantzvolsky this (https://github.com/OmniSharp/omnisharp-roslyn/issues/1493#issuecomment-496284875) works beautifully, especially considering that currently snap is the only package available for Ubuntu 20.04 (will probably change on the release date). Seems to work good enough that I just might keep the snap even when the deb package will be available. Thanks!

[Jozkee]

For anyone that steps in this issue, consider this other workaround as well, I find it easier to apply.
https://github.com/OmniSharp/omnisharp-vscode/issues/3077#issuecomment-498880626