I just upgraded confluence server from 6.11.0 to 6.12.0 however it will not start up. After the installation, confluence showed a screen indicating that our database was using an unsupported driver. I changed the driver class name from
<property name="hibernate.connection.driver_class">net.sourceforge.jtds.jdbc.Driver</property>
to
<property name="hibernate.connection.driver_class">com.microsoft.sqlserver.jdbc.SQLServerDriver</property>
However this did not help. Confluence is started through a batch file.