On this weblog, I’ll evaluation a typical scenario by which Change servers are put in in an outdated Cumulative Replace (CU) model and must be upgraded.
Mainly, this course of shouldn’t be so advanced until .NET compatibility was a difficulty that may have an effect on the entire improve course of.

Change’s CU supportability coverage

In line with the Change serving mannequin since Change 2013 and for all of the On-Premises variations forward, solely the newest 2 CUs variations are supported:

“A CU can be supported for a interval of three (3) months after the discharge date of the subsequent CU. For instance, if CU1 is launched on 3/1 and CU2 is launched on 6/1, CU1 help will finish on 9/1.”

As you most likely know, Change should have .Internet Framework, which needs to be supported by the Cumulative Replace (CU) model you’re working.
For extra data please go to the Change supportability matrix:
https://docs.microsoft.com/en-us/Exchange/plan-and-deploy/supportability-matrix?view=exchserver-2019#microsoft-net-framework

Microsoft supplies Safety Updates for the newest two Cumulative Updates (CUs) launched for Change 2013 and later variations. Prolonged help for Change 2010 ended again in October 2020. Thus, in case your group is working an outdated Change Server model or CU, it’s essential to instantly update your server to the latest CU to proceed receiving the newest Safety Updates (SUs).

When do I’ve a difficulty?

Take into consideration a buyer that runs Change 2016 CU12 and having .NET 4.72 put in on the servers.
This buyer wish to improve his servers to Change 2016 CU16 (at the moment the newest).

In line with the Change supportability matrix, the one .Internet Framework supported by Change 2016 CU16 is .Internet Framework 4.8:

Now this buyer has 2 choices:

1. To be able to be “on the protected aspect”, he wants to put in Change 2016 CU13/CU14 which helps .Internet 4.72 as properly, set up .Internet 4.8 (which helps Change 2016 CU13-CU16) after which improve to Change 2016 CU16.
   The benefit of this course of is that every one alongside the best way, the atmosphere is in a supported state.
   The disadvantages of this course of are, that you just won’t have the earlier CU (CU14 on this instance) since solely the newest CUs are publicly obtainable.
   The opposite drawback is, after all, an extended set up course of particularly if you’re having a big Change atmosphere with many servers.
2. The opposite possibility to put in .Internet 4.8, which is an unsupported state in line with the Change supportability matrix after which improve to Change 2016 CU16.

So learn how to improve within the most secure method?

Please take into account the subsequent essential assertion on the Change supportability matrix article:

“When upgrading Change from an unsupported CU to the present CU and no intermediate CUs can be found, it is best to first improve to the newest model of .NET that’s supported by Change after which instantly improve to the present CU. This methodology doesn’t change the necessity to maintain your Change servers updated and on the newest supported CU.
Microsoft makes no declare that an improve failure is not going to happen utilizing this methodology, which can end in the necessity to contact Microsoft Help Providers.”

Having stated that, since we should improve our Change to a more moderen CU, the subsequent steps ought to happen, so as to full this course of efficiently:

1. Put the Server into Upkeep Mode.
https://docs.microsoft.com/en-us/exchange/high-availability/manage-ha/manage-dags?view=exchserver-2019#performing-maintenance-on-dag-members

2. Cease all the Change Providers.

3. Obtain and set up the proper new .Internet Model in line with the supportability desk.
Understand that this step can take as much as 20 minutes and even 2 hours (had instances like this), subsequently don’t cease the set up and maintain ready till it ends efficiently.

4. After the set up was accomplished, reboot the server.

5. Replace to the most recent Cumulative Replace for Change 2013/2016/2019.

6. Ensure to reboot the server after the CU is put in.

7. Guarantee all Change companies are of their regular begin Mode and began

8. Take the server out of Upkeep Mode.

Suggestions earlier than putting in a brand new CU

There are just a few suggestions that are essential to implement earlier than putting in new CU:

• Reboot the server beforehand.
• Check the brand new CU in a lab/check atmosphere earlier than working it in your manufacturing atmosphere.
• Examine with any third occasion merchandise put in on the Change servers, that they’re supporting the CU model that you’re about to put in.
• Confirm that you’re having spare {hardware} (or sufficient sources in Digital atmosphere) for the RecoverServer course of in case that the set up is not going to full efficiently.
• Examine the Hash file of the CU’s ISO earlier than the set up so as to confirm that the set up will not be corrupted.
  You should utilize the Get-FileHash to confirm that the “SHA256” quantity from VLSC is identical because the file that you’ve got

Should you encounter an error whereas or after upgrading to the newest CU or SU, consult with this Microsoft article. Nevertheless, if the error isn’t fastened, the server fails to start out, or the database will get broken or corrupt throughout the CU improve or SU replace course of, use an Change restoration software program, akin to Stellar Restore for Change. Exchange Server Recovery software can get better mailboxes and restore them out of your failed server to a different dwell Change Server or Workplace 365 instantly.

• Cease any AntiVirus software program put in on the server.
• Run the CU set up utilizing elevated permissions (Run As Administrator).
• Run the set up on an Change server in the identical AD website the place the Area Naming Grasp (AD position) is positioned.
• In line with CU installation process in Microsoft’s web site:
  “Any custom-made Change or Web Info Server (IIS) settings that you just made in Change XML software configuration information on the Change server (for instance, internet.config information or the EdgeTransport.exe.config file) can be overwritten whenever you set up an Change CU.”
  Subsequently, backup any modifications that you’ve got made (in case you probably did).
  These modifications embody after all any Theme modifications like altering the login display screen to OWA for instance.