An issue has been identified in the Exchange Server 2010 SP3 Update Rollup 8. The update has been recalled and is no longer available on the download center pending a new RU8 release. Customers should not proceed with deployments of this update until the new RU8 version is made available. Customers who have already started deployment of RU8 should rollback this update.
The issue impacts the ability of Outlook to connect to Exchange, thus we are taking the action to recall the RU8 to resolve this problem. We will deliver a revised RU8 package as soon as the issue can be isolated, corrected, and validated. We will publish further updates to this blog post regarding RU8.
The bug is in the MAPI RPC layer, clients that use other protocols such as ActiveSync (EAS), Outlook Web App, BlackBerry, and even IMAP4/POP3 all continued to work. Somewhat confusingly, some users reported that Outlook worked just fine or that clients started to work after a while.
This issue only impacts the Exchange Server 2010 SP3 RU8 update, the other updates remain valid and customers can continue with deployment of these packages.
Note: The issue has been fixed on 12th December,2014 Update Rollup 8 v2 For Exchange 2010 SP3 (KB2986475)