Microsoft Re-Releases Update Rollup 4 for Exchange 2010 SP1

Microsoft has announced the re-release of Update Rollup 4 for Exchange Server 2010 SP1. The update was removed from the Microsoft Download Center two weeks ago after customers reported problems with some copy and move operations in mailboxes and public folders.

With the newly released version of Update Rollup 4 Microsoft has issued this upgrade advice to customers:

• Customers who have installed KB 2509910 (Rollup 4, dated June 22, 2011) and KB2581545 (fix for Rollup 4 regression) do not need to install KB 2579150 (re-released Rollup 4) but may do so if they choose to.
• Customers who have already installed KB 2581545 and want to update their systems to the updated Rollup 4 should first uninstall KB 2581545 (or any interim updates) prior to installing the new rollup.
• You do not need to uninstall original RU4 (KB 2509910) to install the re-released RU4 package (KB2579150).
• The re-release of Rollup 4 does not change the release plans for Update Rollup 5 for Exchange Server 2010 Service Pack 1. Rollup 5 is currently scheduled to release in August 2011.

In a separate blog post on the Exchange Team blog Microsoft has explained in more detail what went wrong with Update Rollup 4. The post has a lot of detail in it but the root cause of the issue is described as having come about during the implementation of the RPC Client Access Service in Exchange Server 2010.

…we discovered that there was some specific code added to the Exchange 2003 Information Store to handle the procedure call from Outlook using the extra flag. This code was also carried forward into Exchange 2007. But when the Exchange team added the RPC Client Access service to Exchange 2010, that code was not incorporated into the RPC Client Access service because it was mistakenly believed to be legacy Outlook behavior that was no longer required. That, unfortunately, turned out not to be the case. The fact that we were not allowing a deleted public folder to be recovered was masking this new bug completely.

Microsoft took some heat from Exchange customers over this issue, and in this latest blog post they revealed some details that make it clearer the sort of complexity they are dealing with when it comes to updates for the Exchange Server product.

The Exchange team has well over 100,000 automated tests that we use to validate our product before we ship it. With the richness and number of scenarios and behaviors that Exchange supports, automated testing is the only scalable solution. We execute these tests in varying scenarios and conditions repeatedly before we release the software to our customers. We also supplement these tests with manual validation where necessary. The downside of our tests is that they primarily exercise the interfaces we expose and are designed around our specifications.