Error: nuget configuration is invalid

Question

It's a project in Visual Studio 2015 actually but there is no category of VS2015 in category selection so posting under VS2010. Everything was working fine and suddenly I get this error while I try to add a new nuget package by right clicking on project and select manage nuget packages...:  nuget configuration is invalid Any idea why this can happen?

Shweta Lodha · Answer

For me restarting the visual studio fixed this error. Please try

Nilesh Shah · Answer

No I cannot replicate the error. It occured on its own.

Bryian Tan · Answer

Interesting were you able to replicate this error consistently?

Nilesh Shah · Answer

Thanks but actually the question is not about the solution. Restarting worked for me too but wanted to know why this happened?