.NET Core - The nuget command failed with exit code(1) and error(System.InvalidCastException: Unable to cast object of type 'System.String' to type 'NuGet.Frameworks.NuGetFramework'.
After creating a .NET Core application, I configured our build pipeline to Restore the NuGet packages, Build the application and publish it. Unfortunately the build failed almost immediately.
The build specifically failed on the Restore NuGet packages with the following error message:
The nuget command failed with exit code(1) and error(System.InvalidCastException: Unable to cast object of type 'System.String' to type 'NuGet.Frameworks.NuGetFramework'.
Here are the related build logs:
2019-03-15T15:58:27.7657780Z Attempting to pack file: D:\b\4\agent\_work\83\s\SOFACore\SOFACore.Logging.Exceptions\SOFACore.Logging.Exceptions.csproj
2019-03-15T15:58:27.7706605Z [command]D:\b\4\agent\_work\_tool\NuGet\4.1.0\x64\nuget.exe pack D:\b\4\agent\_work\83\s\SOFACore\SOFACore.Logging.Exceptions\SOFACore.Logging.Exceptions.csproj -NonInteractive -OutputDirectory D:\b\4\agent\_work\83\a -Properties Configuration=Release -version 1.0.0-CI-20190315-165827 -Verbosity Detailed
2019-03-15T15:58:29.7910390Z System.InvalidCastException: Unable to cast object of type 'System.String' to type 'NuGet.Frameworks.NuGetFramework'.
2019-03-15T15:58:29.7910390Z at NuGet.ProjectManagement.NuGetProject.GetMetadata[T](String key)
2019-03-15T15:58:29.7920155Z NuGet Version: 4.1.0.2450
2019-03-15T15:58:29.7920155Z at NuGet.ProjectManagement.PackagesConfigNuGetProject..ctor(String folderPath, Dictionary`2 metadata)
2019-03-15T15:58:29.7920155Z Attempting to build package from ‘SOFACore.Logging.Exceptions.csproj'.
2019-03-15T15:58:29.7920155Z at CallSite.Target(Closure , CallSite , Type , Object , Dictionary`2 )
2019-03-15T15:58:29.7920155Z MSBuild auto-detection: using msbuild version '15.9.21.664' from 'D:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\15.0\bin'. Use option -MSBuildVersion to force nuget to use a specific version of MSBuild.
2019-03-15T15:58:29.7920155Z at System.Dynamic.UpdateDelegates.UpdateAndExecute3[T0,T1,T2,TRet](CallSite site, T0 arg0, T1 arg1, T2 arg2)
2019-03-15T15:58:29.7920155Z at NuGet.CommandLine.ProjectFactory.AddDependencies(Dictionary`2 packagesAndDependencies)
2019-03-15T15:58:29.7920155Z at NuGet.CommandLine.ProjectFactory.ProcessDependencies(PackageBuilder builder)
2019-03-15T15:58:29.7929920Z at NuGet.CommandLine.ProjectFactory.CreateBuilder(String basePath, NuGetVersion version, String suffix, Boolean buildIfNeeded, PackageBuilder builder)
2019-03-15T15:58:29.7929920Z at NuGet.Commands.PackCommandRunner.BuildFromProjectFile(String path)
2019-03-15T15:58:29.7929920Z at NuGet.CommandLine.PackCommand.ExecuteCommand()
2019-03-15T15:58:29.7929920Z at NuGet.CommandLine.Command.ExecuteCommandAsync()
2019-03-15T15:58:29.7929920Z at NuGet.CommandLine.Command.Execute()
2019-03-15T15:58:29.7929920Z at NuGet.CommandLine.Program.MainCore(String workingDirectory, String[] args)
2019-03-15T15:58:29.7929920Z Packing files from 'D:\b\4\agent\_work\83\s\SOFACore\VLM.SOFACore.Logging.Exceptions\bin\Release\netstandard2.0'.
2019-03-15T15:58:29.7929920Z Add file 'D:\b\4\agent\_work\83\s\SOFACore\VLM.SOFACore.Logging.Exceptions\bin\Release\netstandard2.0\VLM.SOFACore.Logging.Exceptions.dll' to package as 'lib\netstandard2.0\VLM.SOFACore.Logging.Exceptions.dll'
2019-03-15T15:58:29.8379110Z ##[error]The nuget command failed with exit code(1) and error(System.InvalidCastException: Unable to cast object of type 'System.String' to type 'NuGet.Frameworks.NuGetFramework'.
at NuGet.ProjectManagement.NuGetProject.GetMetadata[T](String key)
at NuGet.ProjectManagement.PackagesConfigNuGetProject..ctor(String folderPath, Dictionary`2 metadata)
at CallSite.Target(Closure , CallSite , Type , Object , Dictionary`2 )
at System.Dynamic.UpdateDelegates.UpdateAndExecute3[T0,T1,T2,TRet](CallSite site, T0 arg0, T1 arg1, T2 arg2)
at NuGet.CommandLine.ProjectFactory.AddDependencies(Dictionary`2 packagesAndDependencies)
at NuGet.CommandLine.ProjectFactory.ProcessDependencies(PackageBuilder builder)
at NuGet.CommandLine.ProjectFactory.CreateBuilder(String basePath, NuGetVersion version, String suffix, Boolean buildIfNeeded, PackageBuilder builder)
at NuGet.Commands.PackCommandRunner.BuildFromProjectFile(String path)
at NuGet.CommandLine.PackCommand.ExecuteCommand()
at NuGet.CommandLine.Command.ExecuteCommandAsync()
at NuGet.CommandLine.Command.Execute()
at NuGet.CommandLine.Program.MainCore(String workingDirectory, String[] args))
2019-03-15T15:58:29.8388875Z ##[error]An error ocurred while trying to pack the files.
2019-03-15T15:58:29.8388875Z ##[section]Async Command Start: Telemetry
2019-03-15T15:58:29.8388875Z ##[section]Async Command End: Telemetry
2019-03-15T15:58:29.8398640Z ##[section]Async Command Start: Telemetry
2019-03-15T15:58:29.8398640Z ##[section]Async Command End: Telemetry
2019-03-15T15:58:29.8398640Z ##[section]Finishing: NuGet pack
So what is the problem?
This seems to be a known problem;https://github.com/NuGet/Home/issues/4808. The NuGet 4.0 pack command cannot handle .NET Core(and .NET Standard) projects.
There are 2 possible solutions:
- Switch to the .NET Core build task and invoke the dotnet restore command.
- Use the NuGet Tools installer build task to install a newer version of Nuget exe (NuGet 4.9.4 seems to work)