VSTS: ##[error]No value was found for the provided environment variable

Question

I've spent numerous hours trying to figure this one out and simply cannot. FWIW, this projects packs fine from a local command line and from TeamCity. It is also building on VSTS but this error makes the task fail. What environment variable is the Nuget pack task looking for in visualstudio.com build?

Here are the relevant files and the task config:

package.nuspec:

<?xml version="1.0"?>
<package xmlns="http://schemas.microsoft.com/packaging/2011/08/nuspec.xsd">
  <metadata>
    <id>VDS.AppCore.Formatters</id>
    <version>$version$</version>
    <title>VDS AppCore Formatters</title>
    <authors>Visual Data Solutions, Inc.</authors>
    <owners>Visual Data Solutions, Inc.</owners>
    <requireLicenseAcceptance>false</requireLicenseAcceptance>
    <description>VDS AppCore Formatters</description>
    <copyright>Copyright © Visual Data Solutions, Inc. 2010-2017</copyright>
  </metadata>
  <files>
    <file src="$SolutionDir$VDS.AppCore.Formatters\bin\$Configuration$\VDS.AppCore.Formatters.dll" target="lib\net45" />
    <file src="$SolutionDir$VDS.AppCore.Formatters\bin\$Configuration$\VDS.AppCore.Formatters.pdb" target="lib\net45" />
    <file src="$SolutionDir$VDS.AppCore.Formatters\**\*.cs" target="src" />
  </files>
</package>

.csproj

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
  <PropertyGroup>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
    <ProjectGuid>{BED8C9D5-954F-47AA-9BDA-531D125209C0}</ProjectGuid>
    <OutputType>Library</OutputType>
    <AppDesignerFolder>Properties</AppDesignerFolder>
    <RootNamespace>VDS.AppCore.Formatters</RootNamespace>
    <AssemblyName>VDS.AppCore.Formatters</AssemblyName>
    <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
    <FileAlignment>512</FileAlignment>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
    <DebugSymbols>true</DebugSymbols>
    <DebugType>full</DebugType>
    <Optimize>false</Optimize>
    <OutputPath>bin\Debug\</OutputPath>
    <DefineConstants>DEBUG;TRACE</DefineConstants>
    <ErrorReport>prompt</ErrorReport>
    <WarningLevel>4</WarningLevel>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
    <DebugType>pdbonly</DebugType>
    <Optimize>true</Optimize>
    <OutputPath>bin\Release\</OutputPath>
    <DefineConstants>TRACE</DefineConstants>
    <ErrorReport>prompt</ErrorReport>
    <WarningLevel>4</WarningLevel>
  </PropertyGroup>
  <ItemGroup>
    <Reference Include="System" />
    <Reference Include="System.Core" />
    <Reference Include="System.Xml.Linq" />
    <Reference Include="System.Data.DataSetExtensions" />
    <Reference Include="Microsoft.CSharp" />
    <Reference Include="System.Data" />
    <Reference Include="System.Net.Http" />
    <Reference Include="System.Xml" />
  </ItemGroup>
  <ItemGroup>
    <Compile Include="CsvFormatter.cs" />
    <Compile Include="DataFormatters.cs" />
    <Compile Include="DefaultFormatters.cs" />
    <Compile Include="Formatters.cs" />
    <Compile Include="IDataFormatter.cs" />
    <Compile Include="IDataFormatters.cs" />
    <Compile Include="IFlatFormatter.cs" />
    <Compile Include="IFormatters.cs" />
    <Compile Include="Properties\AssemblyInfo.cs" />
    <Compile Include="XlsFormatter.cs" />
  </ItemGroup>
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
</Project>

Any input would be appreciated. This is driving me nuts and is keeping me from moving our build process from an on prem TeamCity to vsts on the cloud which is our current requirement. I really don't want to create a TeamCity VM. :)

Build Log per comments request:

2017-08-16T03:14:26.4967581Z ##[section]Starting: NuGet pack Formatters nuspec
2017-08-16T03:14:26.4967581Z ==============================================================================
2017-08-16T03:14:26.4967581Z Task         : NuGet
2017-08-16T03:14:26.4967581Z Description  : Restore, pack, or push NuGet packages, or run a NuGet command. Supports NuGet.org and authenticated feeds like Package Management and MyGet.
2017-08-16T03:14:26.4967581Z Version      : 2.0.6
2017-08-16T03:14:26.4967581Z Author       : Microsoft Corporation
2017-08-16T03:14:26.4967581Z Help         : [More Information](https://go.microsoft.com/fwlink/?LinkID=613747)
2017-08-16T03:14:26.4977585Z ==============================================================================
2017-08-16T03:14:26.9697601Z [command]C:\Windows\system32\chcp.com 65001
2017-08-16T03:14:26.9787594Z Active code page: 65001
2017-08-16T03:14:26.9917604Z Attempting to pack file: d:\a\1\s\TeamCity\Build\VDS.AppCore.Formatters\Package.nuspec
2017-08-16T03:14:26.9967613Z [command]d:\a\_tool\NuGet\4.0.0\x64\nuget.exe pack d:\a\1\s\TeamCity\Build\VDS.AppCore.Formatters\Package.nuspec -NonInteractive -OutputDirectory d:\a\1\a -Properties Configuration=Debug;SolutionDir=d:\a\1\s\;ArtifactDir=d:\a\1\a;version=2.0.1.71;Platform=AnyCPU -version 2.0.1.71 -Verbosity Detailed
2017-08-16T03:14:27.4699931Z NuGet Version: 4.0.0.2283
2017-08-16T03:14:27.4777604Z Attempting to build package from 'Package.nuspec'.
2017-08-16T03:14:27.6887611Z 
2017-08-16T03:14:27.6907601Z Id: VDS.AppCore.Formatters
2017-08-16T03:14:27.6907601Z Version: 2.0.1.71
2017-08-16T03:14:27.6907601Z Authors: Visual Data Solutions,  Inc.
2017-08-16T03:14:27.6907601Z Description: VDS AppCore Formatters
2017-08-16T03:14:27.6907601Z Dependencies: None
2017-08-16T03:14:27.6907601Z 
2017-08-16T03:14:27.6937601Z Added file '[Content_Types].xml'.
2017-08-16T03:14:27.6937601Z Added file '_rels/.rels'.
2017-08-16T03:14:27.6937601Z Added file 'lib/net45/VDS.AppCore.Formatters.dll'.
2017-08-16T03:14:27.6937601Z Added file 'lib/net45/VDS.AppCore.Formatters.pdb'.
2017-08-16T03:14:27.6937601Z Added file 'package/services/metadata/core-properties/d049e0823aea40cdba6267568d619a5d.psmdcp'.
2017-08-16T03:14:27.6937601Z Added file 'src/CsvFormatter.cs'.
2017-08-16T03:14:27.6937601Z Added file 'src/DataFormatters.cs'.
2017-08-16T03:14:27.6937601Z Added file 'src/DefaultFormatters.cs'.
2017-08-16T03:14:27.6937601Z Added file 'src/Formatters.cs'.
2017-08-16T03:14:27.6937601Z Added file 'src/IDataFormatter.cs'.
2017-08-16T03:14:27.6937601Z Added file 'src/IDataFormatters.cs'.
2017-08-16T03:14:27.6937601Z Added file 'src/IFlatFormatter.cs'.
2017-08-16T03:14:27.6937601Z Added file 'src/IFormatters.cs'.
2017-08-16T03:14:27.6937601Z Added file 'src/Properties/AssemblyInfo.cs'.
2017-08-16T03:14:27.6937601Z Added file 'src/XlsFormatter.cs'.
2017-08-16T03:14:27.6937601Z Added file 'VDS.AppCore.Formatters.nuspec'.
2017-08-16T03:14:27.6937601Z 
2017-08-16T03:14:27.6937601Z Successfully created package 'd:\a\1\a\VDS.AppCore.Formatters.2.0.1.71.nupkg'.
2017-08-16T03:14:27.7427599Z ##[section]Finishing: NuGet pack Formatters nuspec

Answer 1

It caused by the Environment variable option in NuGet pack task.

The variable should be used here without $. So you should use PackageVersion directly.