Unity and VS Code - Getting Omnisharp System.Numerics.Vectors Version Error Stopping Intellisense Working

Question

I've spent 2 days on this error when trying to use Unity with Visual Studio Code as the IDE.

I tried installing various versions of DotNet SDK, Core, Visual Studio, The C# Plugin, nothing worked.

System.IO.FileLoadException: Could not load file or assembly 'System.Numerics.Vectors, Version=4.1.3.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
File name: 'System.Numerics.Vectors, Version=4.1.3.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
   at System.SpanHelpers.SequenceEqual(Byte& first, Byte& second, NUInt length)
   at Microsoft.Extensions.DependencyModel.DependencyContextJsonReader.ReadToEnd(Stream stream)
   at Microsoft.Extensions.DependencyModel.DependencyContextJsonReader.Read(Stream stream)
   at Microsoft.Extensions.DependencyModel.DependencyContextLoader.LoadAssemblyContext(Assembly assembly, IDependencyContextReader reader)
   at Microsoft.Extensions.DependencyModel.DependencyContextLoader.Load(Assembly assembly)
   at Microsoft.Extensions.DependencyModel.DependencyContext.LoadDefault()
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.LazyInitValue()
   at OmniSharp.CompositionHostBuilder.DiscoverOmniSharpAssemblies() in D:\a\1\s\src\OmniSharp.Host\CompositionHostBuilder.cs:line 205
   at OmniSharp.CompositionHostBuilder.WithOmniSharpAssemblies() in D:\a\1\s\src\OmniSharp.Host\CompositionHostBuilder.cs:line 179
   at OmniSharp.Stdio.Driver.Program.<>c__DisplayClass0_1.b__1() in D:\a\1\s\src\OmniSharp.Stdio.Driver\Program.cs:line 56
   at McMaster.Extensions.CommandLineUtils.CommandLineApplication.<>c__DisplayClass146_0.b__0(CancellationToken _)
   at McMaster.Extensions.CommandLineUtils.CommandLineApplication.d__157.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at McMaster.Extensions.CommandLineUtils.CommandLineApplication.Execute(String[] args)
   at OmniSharp.HostHelpers.Start(Func`1 action) in D:\a\1\s\src\OmniSharp.Host\HostHelpers.cs:line 29

=== Pre-bind state information ===
LOG: DisplayName = System.Numerics.Vectors, Version=4.1.3.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
 (Fully-specified)
LOG: Appbase = file:///c:/Users/shaun/.vscode/extensions/ms-dotnettools.csharp-1.23.15/.omnisharp/1.37.15/
LOG: Initial PrivatePath = NULL
Calling assembly : System.Memory, Version=4.0.1.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51.
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: c:\Users\shaun\.vscode\extensions\ms-dotnettools.csharp-1.23.15\.omnisharp\1.37.15\OmniSharp.exe.Config
LOG: Using host configuration file: 
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework64\v4.0.30319\config\machine.config.
LOG: The same bind was seen before, and was failed with hr = 0x80131040.

user_851200 · Answer

If you ever run into this issue, by far the simplest solution is to go into the directory:

Where you will see various versions of this dll that you actually have (assuming you installed various versions of .NET SDK

The one that Omnisharp is looking for is 4.1.3 which of course is not present and is near impossible to install (that I could find).

So in true hacker fashion, make an exact copy of the 4.1.4 folder or maybe the highest that you have, and rename the copy to 4.1.3 like so ....

So, now you have a directory called 4.1.3 which contains the 4.1.4 dll VS Code at next launch finds this and is very happy.

Now of course, if someone can find a real solution without this hack be my guest, but if you want to actually get back up and running in Unity with VS Code and PERFECT Intellisense working on the latest Unity (2021) ... this is the best way to go.

Clues from this pure C# dot net question:

VS Code Omnisharp.MsBuild.Projectmanager can not load assembly System.Numerics.Vectors 4.1.3.0

Unity and VS Code - Getting Omnisharp System.Numerics.Vectors Version Error Stopping Intellisense Working

1 Answers