Users running a breadth of Microsoft Exchange Server versions received updates this week. The company has rolled out updates for Exchange Server 2016, 2013, 2010, and 2007. Each of these releases is a cumulative update, while update rollups were also launched to some ES builds on Tuesday.
Microsoft has explained each cumulative and rollup on its blog. In terms of cumulative updates (CU), the company has sent out CU4 for Exchange 2016 and CU15 for Exchange 2013. Update rollups (RU) offered were RU16 for Exchange 2010 Service Pack 3 and RU22 for Exchange Server 2007 SP3.
There is one key difference between a cumulative update and an update rollup. The rollup patches simply bring a security patch rolled into a general update. Cumulative updates are arguably more familiar and are full server releases that come without a security update, which arrives separately.
Why Microsoft opted for one or the other is unclear and is probably unimportant. What is important is the specifics of each of the new updates, starting with the latest version of Microsoft's mail and calendaring service, Exchange Server 2016.
Exchange Server Updates
CU4 for Exchange Server 2016 – Exchange 2016 has been running on Windows Server 2016 since the latter launched in October. However, users were left frustrated when they had to pause database availability groups (DAG) during installation. Microsoft has fixed the issue, allowing Exchange 2016 to install properly to Windows Server. This only works if CU4 and the security update KB3206632 is in place.
Also added in CU4 is support for .NET Framework 4.6.2, which Microsoft says will be a requirement to run Exchange 2016. Rhoderick Milne, a senior premier field engineer at Microsoft explained this decision in the release notes:
“CU4 supports .NET framework 4.6.2 — while this is an optional upgrade at this time, it makes sense to plan the .NET upgrade as it will become a required pre-requisite for the next CU.”
CU15 Exchange 2013 – Like Exchange Server 2016, CU15 brings .NET framework 4.6.2 support to Exchange 2013. The update also fixes a problem with public folder indexing. This was a carryover issue from the last update where public folder posts were not indexed when public folder migration was active.