Update 1/4/2011: Microsoft has re-released UR3 for Exchange 2007 SP3 with a fix for the problem. Customers who have already deployed UR3 can install this V2 update over the top without uninstalling the original UR3.
Original post continues below.
Microsoft has announced that a small number of customers running Exchange Server 2007 SP3 who have upgraded to Update Rollup 3 (UR3) have experienced a database corruption issue.
As a result of this issue they have removed Update Rollup 3 from the Microsoft website and are advising all customers who have deployed UR3 already to uninstall it.
While only a small number of customers have been affected to date, we believe the risk is significant enough that we are recommending all customers to uninstall Exchange 2007 SP3 RU3 on all Mailbox Servers and Transport servers. Uninstalling the rollup will revert the system back to the previously installed version. We have also removed the Exchange 2007 SP3 RU3 download from the Microsoft Download Center and from Microsoft Update until we are able to produce a new version of the rollup.
The removal steps are not trivial for customers running clustered mailbox servers. The Microsoft Exchange team has provided some guidance in this blog post.
This issue comes hot on the heels of a problem with Exchange 2010 SP1 UR3 that also resulted in that update being removed from the Microsoft website. As Michel De Rooij says:
This isn’t doing the product image any good guys.
Two incidents like this are not going to help customers quickly roll out new updates when they are released. We’ve seen in the past how a bad service pack for an operating system shatters the confidence of system administrators and can take years to repair.