Adding Microsoft.SharePoint.Client reference to project in Visual Studio Code

Question

I'm just starting out with a new Console Application project in VS Code and I need to add a reference to my project for Microsoft.SharePoint.Client using:

dotnet add package Microsoft.SharePoint.Client.dll --version 15.0.4420.1017

However the console returns the following and the .csproj file does not change:

  Determining projects to restore...
  Writing C:\Users\usr1\AppData\Local\Temp\tmpC9C5.tmp
info : Adding PackageReference for package 'Microsoft.SharePoint.Client.dll' into project 'C:\Users\usr1\repo\TstApi\TstApi.csproj'.
info : Restoring packages for C:\Users\usr1\repo\TstApi\TstApi.csproj...
error: NU1101: Unable to find package Microsoft.SharePoint.Client.dll. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
error: Package 'Microsoft.SharePoint.Client.dll' is incompatible with 'all' frameworks in project 'C:\Users\usr1\repo\TstApi\TstApi.csproj'.

Any assistance with this error would be appreciated:

error: NU1101: Unable to find package Microsoft.SharePoint.Client.dll. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages

---

EDIT:

Here's the build error:

dotnet build
Microsoft (R) Build Engine version 16.11.0+0538acc04 for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  All projects are up-to-date for restore.
C:\Users\usr1\repo\TstApi\Program.cs(2,17): error CS0234: The type or namespace name 'SharePoint' does not exist in the namespace 'Microsoft' (are you missing an assembly reference?) [C:\Users\usr1\repo\TstApi\TstApi.csproj]

Build FAILED.

C:\Users\usr1\repo\TstApi\Program.cs(2,17): error CS0234: The type or namespace name 'SharePoint' does not exist in the namespace 'Microsoft' (are you missing an assembly reference?) [C:\Users\usr1\repo\TstApi\TstApi.csproj]
    0 Warning(s)
    1 Error(s)

And here's my csproj and the beginning of my program.cs:

Answer 1

I rolled back my version of dotnet from 5.0.401 to 3.1.413 and it seems to have worked.

First check which version I'm using:

dotnet --version
5.0.401

Then get my installed SDK versions:

dotnet --info

Get my version number for 3.x i.e. "3.1.413":

.NET SDKs installed:
  3.1.413 [C:\Program Files\dotnet\sdk]
  5.0.303 [C:\Program Files\dotnet\sdk]
  5.0.401 [C:\Program Files\dotnet\sdk]

Then switch to that version:

dotnet new globaljson --sdk-version 3.1.413 --force

Then confirm my new version:

dotnet --version
3.1.413

Now when I run my add package it adds the reference to my project and my csproj file reflects the change:

dotnet add package Microsoft.SharePoint.Client.dll --version 15.0.4420.1017