Unable to pack a Nuget Package on VSTS Unable to cast object of type 'System.String' to type 'NuGet.Frameworks.NuGetFramework'

Question

On running \'pack\' I am getting the following error...

2017-07-05T10:37:09.7762333Z ##[section]Starting: NuGet pack
2017-07-05T10:37:09.7762333Z ===========         


        

Answer 1

I had this same issue with my .net standard 2.0 class library I was pack into a nuget package. Here is a screenshot of the step you need to add to replace nuget pack step.

Step Type To Add

Here is how I configured the step

Answer 2

In VSTS I used "dotnet pack" instead of "nuget pack". So this problem was resolved.

To publish nuget lib on VSTS, I choiced the following plugins sequence:

• Get sources
• nuget restore
• dotnet build
• dotnet pack
• nuget push

Answer 3

For pack command to work, you need to ensure that the csproj has the following tags:

<PackageId>*qualified_package_name*</PackageId>
<GeneratePackageOnBuild>true</GeneratePackageOnBuild>

This is particularly relevant if you've migrated from an old-style CSPROJ file

Answer 4

Using Nuget 4.9.1 version resolved my issue.

Answer 5

This seems to be an issue using the Nuget pack item built in to VSTS. I swapped it out for a Command Line element to call dotnet pack instead and it now works.