visual studio 2010 - NuGet Package Manager errors when trying to update

Question

Opening VS2010 today, the extension manager notified me of an update for NuGet Package Manager.

During the install, I get an 'Installation Failed' with an option to view the log.

The key error message I see in that log file is:

The signature on the update version of 'NuGet Package Manager' does not match 
the signature on the installed version. Therefore, Extension Manager cannot 
install the update.

The version numbers I am upgrading from/to are as follows.

Current Version: 1.5.20902.9026  
New Version: 1.6.21205.9031

I have also tried to install it while VS2010 is closed via this page: here

Answer 1

Update: The recently released NuGet 2.0 also may require uninstalling an older version of NuGet first.

From the NuGet 2.0 Release Notes: (http://docs.nuget.org/docs/release-notes/nuget-2.0)

Known Installation Issue

If you are running VS 2010 SP1, you might run into an installation error when attempting to upgrade NuGet if you have an older version installed.

The workaround is to simply uninstall NuGet and then install it from the VS Extension Gallery. See http://support.microsoft.com/kb/2581019 for more information, or to go directly to the VS hotfix.

Note: If Visual Studio won't allow you to uninstall the extension (the Uninstall button is disabled), then you likely need to restart Visual Studio using "Run as Administrator."