As part of Patch Tuesday for the month of August 2013, Microsoft rolled out an update (KB2874216) for Exchange Server 2013. Unfortunately, this update created issues and the company has released a temporary workout (KB2879739) to solve this issue with Exchange Server 2013.
"Late last night we became aware of an issue with MS13-061 security update for Exchange Server 2013. Specifically, after the installation of the security update, the Content Index for mailbox databases shows as Failed and the Microsoft Exchange Search Host Controller service is renamed," Microsoft stated in an official blog post.
According to Microsoft, the security update released during Patch Tuesday resulted in the content index for mailbox databases to show "Failed" on the affected server, as well as a missing Microsoft Exchange Search Host Controller service. The update also caused a new service called "Host Controller service for Exchange." Microsoft acknowledged this issue today stating that the company did not deploy the update into their dogfood environment prior to releasing it.
Microsoft has offered a workaround which involves some registry tweaking, which you can view here. No word on when Microsoft will roll out an update to resolve this issue or when we will see the original update re-released without any issues.