Exchange has a long history of being a solid product, of course it has been bugs in it but they have been addressed with patches and service packs. But the last year or two the set has changed, who doesn’t remember the series of version 2 UR for Exchange 2010 SP about two years ago. My thinking of this is that Microsoft has changed focus from delivering Exchange as regular product with a roadmap of looking forward to a service pack that has a set number of bug-fixes and features. With the service in mind this is not the case to the same extent but rather that the service has become a living thing that constantly are patched and upgraded. With this approach, developers are constantly tossing in new fixes and functionality that sometimes break something else. One reason for this could be that Microsoft is trying to introduce a new feature or fix a problem really fast which is good but it looks like Microsoft is more focused on speed instead of quality it might also be that Microsoft trust and rely on the Managed Availability not to fix the problem but restore functionality for the end-user.
Both myself and customer that for some years now has been comfortable with applying patches as they comes out of Redmond compared to what was the case 15 years ago when patching was something that wasn’t that common. This fear of patching is now back in the Exchange world because of the rollups and CU’s that correct some stuff but also introduce others. Of course the message is to try patches in your lab, but to be honest who has time and can spend money on a lab that mimics your production system? Labs are almost every time smaller and you cannot try everything users do in production. With this several of my customers has now taken a step back and not applying Exchange patches as fast as they would like because of fear breaking things.
Nevertheless Microsoft has now release a version 2 of Exchange 2013 RTM CU2. It mainly addresses the problem with mail enabled Public Folder permissions introduced in CU2 http://blogs.technet.com/b/exchange/archive/2013/07/12/e2013-rtm-cu2-issue-public-folder-permissions-loss-after-pf-mailbox-move.aspx.
The new version 2 of CU has build 712.24 compared to the CU2 712.22. If you already have deployed CU2 you can simply run “setup.exe /m:upgrade /IAcceptExchangeServerLicenseTerms” to install CU2v2.
Download link Exchange 2010 RTM CU2 ver 2 and look on the details to see that you download the correct CU2.
Read Microsoft Exchange team announcement http://blogs.technet.com/b/exchange/archive/2013/07/29/now-available-updated-release-of-exchange-2013-rtm-cu2.aspx