"Error: Unable to find version '1.2.20906.2' of package 'Roslyn.Compilers.CSharp'" when installing packages

What You Are Seeing?

Error when bootstrapping Cake

What is Expected?

No error

What version of Cake are you using?

0.19.3

Are you running on a 32 or 64 bit system?

64

What environment are you running on? Windows? Linux? Mac?

Windows

Are you running on a CI Server? If so, which one?

Reproduced both locally and on TC

How Did You Get This To Happen? (Steps to Reproduce)

(Clean repository, including nuget cache) Run .\build.ps1

Output Log

Downloading and installing Roslyn… Installing packages (using https://packages.nuget.org/api/v2)… Error: System.InvalidOperationException: Unable to find version ‘1.2.20906.2’ of package ‘Roslyn.Compilers.CSharp’. at NuGet.PackageRepositoryHelper.ResolvePackage(IPackageRepository sourceRepository, IPackageRepository localReposito ry, IPackageConstraintProvider constraintProvider, String packageId, SemanticVersion version, Boolean allowPrereleaseVer sions) at NuGet.PackageManager.InstallPackage(String packageId, SemanticVersion version, Boolean ignoreDependencies, Boolean allowPrereleaseVersions) at Cake.Scripting.Roslyn.Stable.RoslynScriptSessionFactory.Install(DirectoryPath root) at Cake.Scripting.Roslyn.Stable.RoslynScriptSessionFactory.CreateSession(IScriptHost host) at Cake.Scripting.Roslyn.RoslynScriptEngine.CreateSession(IScriptHost host, IDictionary2 arguments) at Cake.Core.Scripting.ScriptRunner.Run(IScriptHost host, FilePath scriptPath, IDictionary2 arguments) at Cake.Commands.BuildCommand.Execute(CakeOptions options) at Cake.CakeApplication.Run(CakeOptions options) at Cake.Program.Main()

src/Cake/project.json has the following reference: Roslyn.Compilers.CSharp

Which has been unlisted from nuget: https://www.nuget.org/packages/Roslyn.Compilers.CSharp/

[devlead]

@nagoh FYI nuget.org has been having issues for a few hours, so might be related to that.

[gep13]

NuGet.org, unless there is a strong reason to not, always keeps package versions in place. While they can be unlisted (which removes them from appears on the site and don’t show up in search, installing them directly using the version parameter should always work.