Visual Studio 2019 unable to locate .Net Core SDK

Step 1) First run dotnet --list-sdks from the command line (as in Grzegorz Smulko's answer). Take note of the greatest version number.

Step 2) Create a global.json file at the root of the solution with the exact version number from step 1. it needs to contain all the digits otherwise it wont work. This is the my version at the time of writing

{
  "sdk": {
    "version": "3.1.101"
  }
}

Try running dotnet --list-sdks in the console. According to the info on the pages that appear after downloading .NET Core SDKs from https://dotnet.microsoft.com/download, you need to have version v2.2.106 for VS2017 and v2.2.203 for VS2019.

With only the v2.2.203 installed projects didn't load for me in VS2019. I had to install v2.2.105 too.

I had this problem because I uninstalled some older dotnet SDKs. Not only would VS2019 no longer load dotnet core projects, but dotnet was no longer available on my path and so not available on the command line as simply dotnet.

After installing multiple older versions of dotnet and reparing my VS2019 install, I was finally able to fix it by adding C:\Program Files\dotnet\ to my path. Then VS2019 would load the project again.

Also, none of this affected VS2017, which could load and fully work with the project. And it worked on the command line when I specified the full path to the dotnet executable.

I fixed it by installing the x86 version of the SDK.

It looks like each version of Visual Studio has it's own corresponding dotnet version that it builds on. This is due to msbuild requirements.

If you are a Visual Studio user, there are MSBuild version requirements so use only the .NET Core SDK supported for each Visual Studio version. If you use other development environments, we recommend using the latest SDK release.

https://github.com/dotnet/core/blob/master/release-notes/2.2/2.2.6/2.2.6.md

As detailed on that page, you'll need the following versions of dotnet for each visual studio version:

• Visual Studio 2017 (Windows): .NET Core SDK x86 2.2.108
• Visual Studio 2019 version 16.0: .NET Core SDK x86 2.2.205
• Visual Studio 2019 version 16.1: .NET Core SDK x86 2.2.301
• Visual Studio 2019 version 16.2: .NET Core SDK x86 2.2.401