Exchange 2013 CU6 databases unexpectedly fail over in a co-existence environment with Exchange 2007: This is an issue that has come up after the release of Exchange 2013 CU6. The details of this issue are available in KB:2997209– “Exchange Server 2013 databases unexpectedly fail over in a co-existence environment with Exchange Server 2007”
A fix is available for this issue from Microsoft Support.
You cannot route ActiveSync traffic to Exchange 2007 mailboxes after you upgrade to Exchange 2013 CU6: The details of this issue are available in KB:2997847– “You cannot route ActiveSync traffic to Exchange 2007 mailboxes after you upgrade to Exchange 2013 CU6”.
A fix is available for this issue from Microsoft Support.
Exchange Online mailboxes cannot be managed by using EAC (Exchange Administration Center) after you deploy Exchange 2013 CU6: This is another issue that has come up after the release of Exchange 2013 CU6. The details of this issue are available in KB:2997355– “Exchange Online mailboxes cannot be managed by using EAC after you deploy Exchange Server 2013 CU6”
A script is available for this issue from Microsoft Support.
Please be advised if you installed Exchange in an alternate location (other than the default) then you would need to modify the directory path in the script.