After installation of Visual Studio 2013, an existing SQL server data tools project in VS2010 on the same machine would no longer build. The exception in the error window read “The “SqlBuildTask” task failed unexpectedly. System.MissingMethodException: Method not found: ‘Void Microsoft.Data.Tools.Schema.SchemaModel.DataSchemaModel.Serialize” (…)

Fortunately, the solution was rather simple. It turns out there is a new version (October 2013) of the SQL Server Data Tools available at the Microsoft download site. Simply installing that over my existing installation fixed things. Note that I did get a Visual Studio conversion wizard the time first opened the project after that, but that conversion went seamlessly.

Thanks to Michael Mairegger for the tip. He had the same issue after installing a service pack for SQL server management studio.

Note that the same also appears to apply to VS2012.