installing nuget package “same key has already been added.”

Question

i am trying to install Microsoft.Bcl.Build 1.0.14

nuget returns

Installing \'Microsoft.Bcl.Build 1.0.14\'. Successfully installed \'Microsoft.Bcl.Bu         


        

Answer 1

Check your packages.config Inside there, check for the packages you are trying to install. Maybe some reference are already there and this avoid that you can install the new ones.

If you find there the references, delete the reference from the packages.config and try to install again the package.

It happened to me sometimes that inside packages.config are some old reference that still left there even after removing the package from the Nuget Package Manager.

If not, you can delete the entire packages.config, then if you have the option to let Nuget download the packages, when you build your solution, the packages will be downloaded again.

I hope this helps

Answer 2

I just had a exatly the same problem, but installing the latest update for the NuGet Package Manager solved the problem.

Answer 3

Go into your packages directory and delete all version of the package you don't need anymore.

Then try installing the correct version. I think it is looking at all the folders in that directory and trying to add them to some kind of dictionary/hashset and finding two.

Answer 4

This happens in the .Net Core and .Net Standard Portable Class Library space a lot. Even though I have not traced the true root of the problem it seems to happen most when I directly modify the project.json dependencies section with packages that have a lot of other external dependencies (that have terms associated with them).

If you can identify the library responsible and remove all the dependencies and use the proper nuget package management tool to add the packages. It has not uncommon to have to delete and recreate the CLI completely!

Answer 5

Just update the Nuget package manager in tools -- extension and updates -- updates --visual studio gallery --update Nuget package manager

Answer 6

I had a similar problem. It was corrected when I removed duplicate PackageReference elements with the specified package in the project’s .csproj file using notepad.