EntityFramework 6 breaks Backup/Restore of LocalDB.
EntityFramework 6 has lots of Resiliency enhancements, but one of the side effects is that doing a backup or restore of a LocalDB database will need a tweak to keep EF from spinning up a transaction around the SQL statement.
Essentially, when you call ExecuteSqlCommand, you have to request that it does NOT ensure the a transaction exists with the first parameter of TransactionalBehavior.DoNotEnsureTransaction.
I have updated the appropriate posts:
How to backup a LocalDB database under an MVC 4 sytem
Restoring a LocalDB within an MVC web application