title: VSTS build: Packages failed to restore - Unable to resolve 'NETStandard.Library (>= 1.6.1)' for '.NETStandard,Version=v2.0'
body: <p>I'm getting </p>
  
  <blockquote>
    <p>Unable to resolve 'NETStandard.Library (>= 1.6.1)' for '.NETStandard,Version=v2.0'.</p>
  </blockquote>
  
  <p>in VSTS build using Hosted2017 build agent after I upgraded my aspnetcore app to <code>netcoreapp2.0</code> and my libraries to use <code>netstandard2.0</code>. </p>
  
  <p>Works fine locally.</p>
  
  <p>I've edited my build definition to use .net core build task <code>v2.* preview</code>:</p>
  
  <p><a href="https://i.stack.imgur.com/3B8Q1.png" rel="noreferrer"><img src="https://i.stack.imgur.com/3B8Q1.png" alt="build definition details"></a></p>
  
  <p>here is the build log:</p>
  
  <pre><code>Current agent version: '2.120.2'
  Download all required tasks.
  Downloading task: DotNetCoreCLI
  
  Starting: Get Sources
  Syncing repository: Liero/vyvojari-sk (GitHub)
  ...details ommited
  HEAD is now at e448a25... Upgraded to .NET Core 2.0
  Finishing: Get Sources
  
  Starting: Restore
  ==============================================================================
  Task         : .NET Core
  Description  : Build, test, package, or publish a dotnet application, or run a custom dotnet command. For package commands, supports NuGet.org and authenticated feeds like Package Management and MyGet.
  Version      : 2.0.5
  Author       : Microsoft Corporation
  Help         : [More Information](https://go.microsoft.com/fwlink/?linkid=832194)
  ==============================================================================
  SYSTEMVSSCONNECTION exists true
  Downloading: https://dist.nuget.org/win-x86-commandline/v4.0.0/nuget.exe
  Caching tool: NuGet 4.0.0 x64
  Using version: 4.0.0
  Found tool in cache: NuGet 4.0.0 x64
  Saving NuGet.config to a temporary config file.
  Can\'t find loc string for key: NGCommon_NoSourcesFoundInConfig
  NGCommon_NoSourcesFoundInConfig d:\a\1\Nuget\tempNuGet_734.config
  "C:\Program Files\dotnet\dotnet.exe" restore d:\a\1\s\src\CommandStack\CommandStack.csproj --configfile d:\a\1\Nuget\tempNuGet_734.config --verbosity Detailed
    Restoring packages for d:\a\1\s\src\CommandStack\CommandStack.csproj...
  C:\Program Files\dotnet\sdk\1.0.4\NuGet.targets(97,5): error : Unable to resolve 'NETStandard.Library (&gt;= 1.6.1)' for '.NETStandard,Version=v2.0'. [d:\a\1\s\src\CommandStack\CommandStack.csproj]
    Generating MSBuild file d:\a\1\s\src\CommandStack\obj\CommandStack.csproj.nuget.g.props.
    Generating MSBuild file d:\a\1\s\src\CommandStack\obj\CommandStack.csproj.nuget.g.targets.
    Writing lock file to disk. Path: d:\a\1\s\src\CommandStack\obj\project.assets.json
    Restore failed in 115.64 ms for d:\a\1\s\src\CommandStack\CommandStack.csproj.
  
    Errors in d:\a\1\s\src\CommandStack\CommandStack.csproj
        Unable to resolve 'NETStandard.Library (&gt;= 1.6.1)' for '.NETStandard,Version=v2.0'.
  
    NuGet Config files used:
        d:\a\1\Nuget\tempNuGet_734.config
  Error: C:\Program Files\dotnet\dotnet.exe failed with return code: 1
  Packages failed to restore
  ******************************************************************************
  Finishing: Restore
  ******************************************************************************
  </code></pre>
  
  <p>and here is the source code: <a href="https://github.com/Liero/vyvojari-sk/tree/e448a25fb8c481704e9102aaaeb8b84b9aee7b02" rel="noreferrer">https://github.com/Liero/vyvojari-sk/tree/e448a25fb8c481704e9102aaaeb8b84b9aee7b02</a></p>