Visual Studio SQL Compare - Cannot Update or Generate Script

Using SQL Compare in Visual Studio is kinda great.

However if you find you cannot generate the change script, or update the database directly after comparing because the Update and Generate Script buttons are greyed-out / disabled (see below), this may be the reason: the version of the .NET framework.

Right-click on the database project, select Properties and go to the SQLCLR tab and change the Target Framework version.