$SQLconnection = New-Object System.Data.SqlClient.SqlConnection $SQLconnection.ConnectionString = \"Server = MySQLservername\\MSSQLSERVER; Database = \"MYSQLDB\"; In
As far as I am aware, it has never been a requirement to quote the server or databasename in a connection string. You should be using this
$SQLconnection.ConnectionString = "Server=MySQLservername\MSSQLSERVER;Database=MYSQLDB;Integrated Security=True"