Fixing The SignatureMismatchException When Updating NuGet

Recently I was trying to update the NuGet Package Manager for VS.NET 2010 from version 1.6.x to 1.7.x and ran across the following exception in the log presented when there is an error with the update process:

VSIXInstaller.SignatureMismatchException: The installed version of 'NuGet Package Manager' is signed, but the update version has an invalid signature. Therefore, Extension Manager cannot install the update. at VSIXInstaller.Common.VerifyMatchingExtensionSignatures(IInstalledExtension installedExtension, IInstallableExtension updateExtension) at VSIXInstaller.InstallProgressPage.BeginInstallVSIX(SupportedVSSKU targetAppID)
Install Error : VSIXInstaller.SignatureMismatchException: The installed version of 'NuGet Package Manager' is signed, but the update version has an invalid signature. Therefore, Extension Manager cannot install the update at. VSIXInstaller.Common.VerifyMatchingExtensionSignatures(IInstalledExtension installedExtension, IInstallableExtension updateExtension) at VSIXInstaller.InstallProgressPage.BeginInstallVSIX(SupportedVSSKU targetAppID)

The fix is simple; it requires an uninstall and reinstall. I assume updates within a version would work, but since I am actually upgrading I imagine this is what requires the uninstall 1st.

Go back to the Extension Manager and select "Installed Extensions", and then select the NuGet pacakage and press "Uninstall". Close and reopen the Extension Manager to refresh the installed packages, and search the Online Gallery for NuGet. If ordering by "Highest Ranked" it typically is the 1st or close to 1st item in the list. Now select "Download" and the installation will complete successfully.

Adding The HTML Target Schema Selection to VS.NET 2010 for HTML5 Intellisense

If you are beginning to delve into HTML5 in VS.NET say in a MVC3 project using the Razor engine for example, you will want intellisense support for HTML5. This is not difficult to do, but the 'HTML Source Editing' toolbar may not be shown by default in your VS.NET instance. To add it preform the following steps:

1. Open VS.NET but do not open any specific project. This ensures the changes you make will be for all project's opened.

2. Go to 'View -> Toolbars' and select the 'HTML Source Editing' menu item.

3. To test, open a MVC3 or MVC4 project using the Razor engine and navigate to a .cshtml view. The dropdown will now be active and the default selection will be 'XHTML 1.0 Transitional'. Change it to 'HTML5'.

4. Now try typing in the first few letters of a HTML element or attribute, like the 'Canvas' tag.

You now have the HTML5 schema validation and intellisense support.