title: An error occurred when executing task 'Build'
body: <h3>Issue / Steps to reproduce the problem</h3>
  
  <p>Running build.ps1 file inside IdentityServer4/src/IdentityServer4/</p>
  
  <p>This build issue was generated while building <code>IdentityServer4</code> project independently. i.e. IdentityServer4 project is isolated from other project.</p>
  
  <h3>Relevant parts of the log file</h3>
  
  <pre><code>Using global .NET SDK
  
  ----------------------------------------
  Setup
  ----------------------------------------
  branch            : master
  pre-release label :
  version           : 0.1.0.0
  version suffix    :
  informational     : 0.1.0+1.Branch.master.Sha.e333ebb1284752e0e62ed4e9637961dce3aac501
  
  ========================================
  Clean
  ========================================
  
  ========================================
  Build
  ========================================
  Microsoft (R) Build Engine version 15.9.20+g88f5fadfbe for .NET Core
  Copyright (C) Microsoft Corporation. All rights reserved.
  
    Restoring packages for D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj...
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency IdentityModel does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency IdentityServer4.Storage does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.AspNetCore.Authentication does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.AspNetCore.Authentication.Cookies does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.AspNetCore.Authentication.OpenIdConnect does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.AspNetCore.Authorization does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.AspNetCore.Cors does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.Extensions.Caching.Memory does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.Extensions.Logging does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.Extensions.Options.ConfigurationExtensions does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.SourceLink.GitHub does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency System.IdentityModel.Tokens.Jwt does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency System.Security.Cryptography.Cng does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : error NU1103: Unable to find a stable package Microsoft.SourceLink.GitHub with version
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : error NU1103:   - Found 7 version(s) in nuget.org [ Nearest version: 1.0.0-beta-62905-03 ]
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : error NU1103:   - Found 0 version(s) in Microsoft Visual Studio Offline Packages
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1701: Package 'IdentityModel 1.0.0' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1701: Package 'System.IdentityModel.Tokens.Jwt 1.0.0' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project.
    Generating MSBuild file D:\IdentityServer4\IdentityServer4\src\obj\IdentityServer4.csproj.nuget.g.props.
    Generating MSBuild file D:\IdentityServer4\IdentityServer4\src\obj\IdentityServer4.csproj.nuget.g.targets.
    Restore failed in 946.03 ms for D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj.
  
  Build FAILED.
  
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency IdentityModel does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency IdentityServer4.Storage does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.AspNetCore.Authentication does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.AspNetCore.Authentication.Cookies does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.AspNetCore.Authentication.OpenIdConnect does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.AspNetCore.Authorization does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.AspNetCore.Cors does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.Extensions.Caching.Memory does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.Extensions.Logging does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.Extensions.Options.ConfigurationExtensions does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency Microsoft.SourceLink.GitHub does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency System.IdentityModel.Tokens.Jwt does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1604: Project dependency System.Security.Cryptography.Cng does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1701: Package 'IdentityModel 1.0.0' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : warning NU1701: Package 'System.IdentityModel.Tokens.Jwt 1.0.0' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project.
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : error NU1103: Unable to find a stable package Microsoft.SourceLink.GitHub with version
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : error NU1103:   - Found 7 version(s) in nuget.org [ Nearest version: 1.0.0-beta-62905-03 ]
  D:\IdentityServer4\IdentityServer4\src\IdentityServer4.csproj : error NU1103:   - Found 0 version(s) in Microsoft Visual Studio Offline Packages
      15 Warning(s)
      1 Error(s)
  
  Time Elapsed 00:00:01.48
  An error occurred when executing task 'Build'.
  Error: One or more errors occurred. (.NET Core CLI: Process returned an error (exit code 1).)
          .NET Core CLI: Process returned an error (exit code 1).
  </code></pre>
  
  <p>How can is solve this issue?</p>