Exchange 2019 CU8 and Exchange 2016 CU19

Exchange CU

Hello fellow Exchange Admins! I know I am late on this. This post is for the records to have all CUs we installed covered. Anyway, we started to install Exchange 2019 CU8 and Exchange 2016 CU19 on the 4th of march straight after the Microsoft out of band session regarding Hafnium.

Altogether our environment consists of Exchange 2016 and Exchange 2019 servers. Therefore we needed to apply the highest schema prior to installing Exchange 2019 CU8 and Exchange 2016 CU19 in this mixed environment.

Accordingly, we ran /prepareschema,/preparead,/preparedomain from an Exchange 2019 server. That was the first server in our environment we upgraded.

In order to determine your current schema version use the commands below:

Forest Range Upper:
Get-ADObject “CN=ms-Exch-Schema-Version-Pt,$((Get-ADRootDSE).schemaNamingContext)” -Property Rangeupper

Forest Object Version:
Get-ADObject (dir “AD:\CN=Microsoft Exchange,CN=Services,$((Get-ADRootDSE).configurationNamingContext)”).DistinguishedName -Property objectVersion

Domain Object Version:
Get-ADObject “CN=Microsoft Exchange System Objects,$((Get-ADRootDSE).defaultNamingContext)” -Property objectVersion

After you have determined your current schema versions check the minimum schema version required to install Exchange 2019 CU8 or Exchange 2016 CU19 from this handy list on

Tasks before installing Exchange 2019 CU8 and Exchange 2016 CU19:

  • Backup your web.config files where you have modified parameters or have added new keys.

    As we experienced it still only the web.config file in the OWA directory takes over parameters and keys you have modified before. To be safe I recommend backup every web.config file you have ever touched/modified. So you can easily reapply the changes you have made.

  • Disable Check for publisher’s certificate revocation in IE.
  • Make sure you have enough free space on the install drive.
  • Take a look at the supportability matrix if you need to upgrade your .NET version.
  • Check Auth methods on service directories like Powershell, OWA, and ECP and note the output.
  • Switch mailbox databases and put the server in maintenance mode.

Order of install:

  • Install the regular Windows patches ( if necessary )
  • Install Exchange 2019 CU8 or Exchange 2016 CU19
  • Install the Hafnium patch KB5000871 from an elevated Command Prompt


Experiences after Exchange 2019 CU8 and Exchange 2016 CU19 has been installed:

  • We had mailtips disabled. Mailtips were enabled afterward.
  • The web.config files in the following directories have been overwritten. Changes needed to be reapplied.

    Active Sync – [ We have an increased attachment size ] :

    C:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\sync
    C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\sync

    ECP – [ We have additional keys in place. ] :

    C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\exchweb\ews

    Anyway, I always check the OWA web.config as well:

    OWA – [ We have additional keys in place ] :

    C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\Owa

  • Virtual directories for additional OWA and ECP we have in place needed to be recreated.
  • Problems with Exchange 2019 CU8 and Exchange 2016 CU19:

    As mentioned above we started to upgrade our Exchange 2019 servers first. After the first server was upgraded customers reported that delegated users lost their access rights on shared mailboxes. This was a minor issue since only a few customers were affected and could be solved by reapplying those access rights.

    Another issue that started after we had the CU in place was time-outs from a 3rd party archiving software. Nothing fatally critical but from time to time some mailboxes could not be archived because the process ran into a time out. On the next run, those mailboxes were archived but new ones ran into a time-out.

    However, in the event log of the patched servers, we could find the event IDs Microsoft mentions in this article. Microsoft states that upgrading to Exchange 2019 CU9 will solve the problem.
    As soon as we upgrade to Exchange 2019 CU9 I will update this post.


In case you need information on other CUs take a look into the CU Archives

… or find a general description here: CU Install Exchange

Stay safe!

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