https://support.microsoft.com/en-us/topic/kb2894326-an-application-cannot-connect-to-a-contained-database-when-connection-pooling-is-enabled-in-sql-server-2012-or-sql-server-2014-75c8491e-125d-7918-a707-2ad843ff5489
KB2894326 - An application cannot connect to a contained database when connection pooling is...
Fixes a problem in which an application cannot connect to a contained database when connection pooling is enabled in SQL Server 2012 or SQL Server 2014.