Roslyn open solution NullReferenceException

user_14034129 0
Viewed 641

I am using .Net 4.8 Console project with such NuGet packages

Microsoft.CodeAnalysis.CSharp.3.8.0
Microsoft.CodeAnalysis.CSharp.Workspaces.3.8.0
Microsoft.CodeAnalysis.Workspaces.MSBuild.3.8.0

Program.cs

MSBuildWorkspace workspace = MSBuildWorkspace.Create();
Solution currSolution = workspace.OpenSolutionAsync(@"C:\Users\***\source\repos\WpfApp5\WpfApp5.sln").Result;

OpenSolutionAsync throwing exception

Object reference not set to an instance of an object.

Stack trace

at Microsoft.Build.Shared.BuildEnvironmentHelper.get_Instance()
   at Microsoft.Build.Utilities.Traits.get_Instance()
   at Microsoft.Build.Evaluation.ProjectCollection..ctor(IDictionary`2 globalProperties, IEnumerable`1 loggers, IEnumerable`1 remoteLoggers, ToolsetDefinitionLocations toolsetDefinitionLocations, Int32 maxNodeCount, Boolean onlyLogCriticalEvents, Boolean loadProjectsReadOnly)
   at Microsoft.CodeAnalysis.MSBuild.Build.ProjectBuildManager.StartBatchBuild(IDictionary`2 globalProperties)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.<LoadAsync>d__19.MoveNext()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.<LoadSolutionInfoAsync>d__21.MoveNext()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.<OpenSolutionAsync>d__24.MoveNext()

I found only this issue and its looks like this error already not fixed for 5 years? Is there any solution or workaround that allows to open solution?

roslyn c#
2 Answers

I was facing a similar issue in a console app (.NET framework 4.7.2). I followed the instructions listed in Using MSBuildWorkspace and it solved the issue for me.

The solution was to remove all Microsoft.Build.* references other than Microsoft.Build.Locator, and to add MSBuildLocator.RegisterDefaults(); before attempting to create a workspace.

This is what the code looks like:

using Microsoft.Build.Locator;
using Microsoft.CodeAnalysis.MSBuild;

...

MSBuildLocator.RegisterDefaults();

using (var workspace = MSBuildWorkspace.Create())
{
    // Use MSBuildWorkspace...
}
user_107558810

Try and remove the packages as a .net framework 4.8 should not need them as it uses references to the framework, not NuGet

Update after comment. When I create a new Console application with .net framework and unload it the following csproj file is shown, there is no need NuGet Packages.

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
  <PropertyGroup>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
    <ProjectGuid>{F1E9931B-351C-41B2-AC30-18E41A244675}</ProjectGuid>
    <OutputType>Exe</OutputType>
    <RootNamespace>ConsoleApp2</RootNamespace>
    <AssemblyName>ConsoleApp2</AssemblyName>
    <TargetFrameworkVersion>v4.8</TargetFrameworkVersion>
    <FileAlignment>512</FileAlignment>
    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
    <Deterministic>true</Deterministic>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
    <PlatformTarget>AnyCPU</PlatformTarget>
    <DebugSymbols>true</DebugSymbols>
    <DebugType>full</DebugType>
    <Optimize>false</Optimize>
    <OutputPath>bin\Debug\</OutputPath>
    <DefineConstants>DEBUG;TRACE</DefineConstants>
    <ErrorReport>prompt</ErrorReport>
    <WarningLevel>4</WarningLevel>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
    <PlatformTarget>AnyCPU</PlatformTarget>
    <DebugType>pdbonly</DebugType>
    <Optimize>true</Optimize>
    <OutputPath>bin\Release\</OutputPath>
    <DefineConstants>TRACE</DefineConstants>
    <ErrorReport>prompt</ErrorReport>
    <WarningLevel>4</WarningLevel>
  </PropertyGroup>
  <ItemGroup>
    <Reference Include="System" />
    <Reference Include="System.Core" />
    <Reference Include="System.Xml.Linq" />
    <Reference Include="System.Data.DataSetExtensions" />
    <Reference Include="Microsoft.CSharp" />
    <Reference Include="System.Data" />
    <Reference Include="System.Net.Http" />
    <Reference Include="System.Xml" />
  </ItemGroup>
  <ItemGroup>
    <Compile Include="Program.cs" />
    <Compile Include="Properties\AssemblyInfo.cs" />
  </ItemGroup>
  <ItemGroup>
    <None Include="App.config" />
  </ItemGroup>
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
</Project>

After validate you can get it back by right-clicking the solution again and select "reload"

user_80003820
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