Visual studio 2017 Update 3 - The SDK 'Microsoft.NET.Sdk.Web' specified could not be found

I stumbled upon this issue a number of times recently. Here's a brief list of the workaround I found (one of them always worked until now):

1. Install the right .NET Core SDK: Either the latest version or the version required by your project.
2. Clean-up obsolete .NET Core versions: Go to Control Panel and uninstall previous .NET Core SDK/Runtime versions (as long as you don't use them anymore).

3. Create a Global.json file: Add a new global.json file to your project's root with the following content (replace the .NET Core version build with the one you want to run the project with):

   { "sdk": { "version": "2.0.5" } }

4. Rename the SDK reference: Open your .proj file and replace <project sdk="Microsoft.NET.Sdk.web"> with <project sdk="Microsoft.NET.Sdk"> .

5. Add the MSBuildSDKsPath Environment Variable: The dotnet CLI sets the MSBuildSDKsPath environment variable when invoking MSBuild: however, a December 2016 patch changed the CLI behaviour so that it will respect an existing environment variable, if it has already been set: this will allow the developer to “force” the CLI to use a specific SDK.

6. Check your PATH: Verify that both C:\Program Files\dotnet and C:\Program Files (x86)\dotnet are in the PATH environment variable.

For additional info regarding the issue and other viable fixes check out this blog post that I wrote on this topic.

As suggested in the comment, I updated global.json file as shown below

{
  "sdk": {
  "version": "1.0.0"
 } 
}

Also, I had to remove the <ItemGroup> which contains wwwroot files path in .csproj file.

Reload the project and it works like a charm!

I agree with the comment on Sundeep's answer, you shouldn't have a global.json file in your project anymore.

It seems as though installing the .NET Core 2.0 SDK is causing issues with the PATH. Verify that C:\Program Files\dotnet and C:\Program Files (x86)\dotnet are in the PATH environment variable. In my case, these values were already present under System Variables so I added them to User Variables and rebooted my machine. This resolved my issue.