A quick heads-up that when you are running Exchange Server 2013, you should not install or update to .NET Framework 4.6. This version of the .NET framework is not only not supported, it may also cause your Exchange 2013 server to stop functioning correctly.
When you have updated from a previous version, a suggested workaround is to uninstall .NET Framework 4.6. However, with all the dependencies on the .NET Framework by Exchange Server, it maybe preferred, when you did install version .NET Framework 4.6, to migrate contents, i.e. mailboxes etc., to a new Exchange 2013 server, and decommission the one you installed .NET 4.6.
More information can be found in KB3095369.