Update – 2/15/2018
There may be a change in the way that Microsoft will support upgrades from older CU’s to the latest CU of Exchange 2013 or 2016. If we review the Exchange Server Supportability Matrix we see that in the .NET section, there is this note:
- “When upgrading Exchange from an unsupported CU to the current CU and no intermediate CUs are available, you should upgrade to the latest version of .NET that’s supported by Exchange first and then immediately upgrade to the current CU. This method doesn’t replace the need to keep your Exchange servers up to date and on the latest, supported, CU. Microsoft makes no claim that an upgrade failure will not occur using this method, which may result in the need to contact Microsoft Support Services. “
Reading this it tells me that while an upgrade from an old, unsupported CU to a newer supporter is allowed, there is no guarantee it will work. If it fails, a call to Microsoft support is needed. This clarification seems to eliminate the need for the Bridge CU (CU15) and may allow for a direct path for an upgrade. I would take this note with a grain of salt as there is no guarantee it would work. This upgrade path is a hard one for Microsoft to predict as there are quite a few CUs for Exchange 2013 now and there are endless possibilities for this to fail when upgrading .NET and then upgrading to the latest CU. Proceed with caution.
Update – 11/15/2017
So a client of mine is upgrading Exchange 2013 from CU5 to CU18 this weekend. He asked what he could do to prep in order to reduce our upgrade time. The obvious one is to download all update beforehand and stage them on the servers to be upgraded. However, he was only able to get CU18 as CU15 is no longer available. So the bridge has washed out. If you need this update, you may be able to contact Microsoft? By YMMV on this one.
End of Update
Update – 9/29/2017
It appears that Microsoft has decided to leave the CU15 update as downloadable for now. Even though, as of this update, CU18 is out and only CU16 to CU18 should be out, CU15 is still available. CU14, however, has joined the ranks of the removed downloads…. I wonder how long this will last?
End of Update
For those of you who support Exchange 2013, you may be aware of the availability of CUs for Exchange 2013. If you are not, then simply put, when a new CU comes out, only that CU and the previous CU are available for Public download. There will be some interim time when the previous CU (CU-2) is also available, but that too shall pass. Currently Microsoft is now up to CU17 for Exchange 2013.
- CU – Cumulative Update – Microsoft’s quarterly update for Exchange server
What this means is that CU17 and CU16 will eventually be the only updates for Exchange 2013 out there. While CU15 is still available at the time of this post, that again shall disappear.
If you are running any version of Exchange 2013 that is CU14 or lower, this is going to cause you some headache if you need to update to the latest CU. Microsoft put in a .NET requirements that makes it impossible to go directly from CU14 and before to CU16 or CU17. These latest Cumulative Updates require .NET 4.6.2 BEFORE you can install them. However, CU14 and before only support up to .NET 4.6.1. See the Exchange 2013 Supportability Matrix for more information on what is supported.
According to Microsoft, the process for moving from an older to the latest CU would require 3 steps:
- Install Exchange 2013 CU15
- Upgrade .NET to 4.6.2
- Install Exchange 2013 CU17
There is only one problem with this scenario. Unless you were fortuitous to have downloaded CU15 prior to the upgrade, the download for Exchange 2013 CU15 is not available from Microsoft.
Here are two scenarios that could potentially trigger this conundrum.
Consider the case where management has decided to pursue an investment in cloud services like Office 365. In their pursuit of this directive, the existing infrastructure was examined and a consultant brought in to help determine what upgrades need to be made to migrate to Office 265. When a health check of Exchange was performed, it was realized that the servers were far behind in their patch maintenance as Exchange 2013 CU9 is installed on all Exchange servers. According to the consultant (who knows Microsoft’s official statement), the Exchange Servers need to be CU16 or CU17 (CU17 is the latest CU for Exchange 2013).
A new IT Director is hired due to lack of due diligence by the previous IT management. When this new Director arrives, a health check and survey of the existing services is ordered. It is found that patch management is lax. The Exchange server is running Exchange 2013 CU10 which is almost two years behind the latest release. As such a plan must be made in order to bring these servers back into support from Microsoft.
In both the above scenarios, the three-step process is needed in order to get to the desired end state. At some point in time, the availability of CU15 will be removed from the Public Download space. This means that if you are in either of those scenarios you would need to open up a support call with Microsoft in order to get your download:
The only real solution is to download the CU updates and store them either on a file server or in a cloud file storage service for later retrieval. At the very least you would need your current CU, CU15 and the latest CU. I would also recommend having versions of .NET available as well in case the support for those components change as well.
While I understand Microsoft’s thought process for requiring the latest updates and keeping current, the IT world is notorious for not always being up to date. Not being able to download older updates, I think, is a bit short-sighted when it comes to a major product like Exchange Server. While downloads for .NET that are over two years old and some updates for Exchange Server 2010 that are almost 4 years old can still be downloaded. We know that this policy isn’t likely to be changed as it has been in place for quite some time and not enough customers have complained about the availability. So in short, if you are still on Exchange 2013, make sure you have a copy of your current CU and CU15 if you are in this scenario.