The Exchange Team released the quarterly Cumulative Updates for Exchange Server 2019 as well as Exchange 2016. Like the previous Cumulative Updates, these require .NET Framework 4.8. Apart from fixes as well as security updates included from the previous CU, these update contain the following changes for Exchange 2019 CU5:

• Updated Exchange calculator (v10.4).
• Fixes an issue with Manage-MetaCacheDatabase.ps1 to configure MCDB.
• Fixes partial word searches when using Outlook in online mode.

Links to the updates as well as a description of changes and fixes are described below.

Version	Build	KB	Download	UMLP	Schema
Exchange 2019 CU5	15.2.595.3	KB4537677	VLSC		N
Exchange 2016 CU16	15.1.1979.3	KB4537678	Download	UMLP	N

Exchange 2019 CU5 fixes:

• 4552472 Exchange Server 2019 Sizing Calculator version 10.4 is available
• 4536552 Export-ModernPublicFolderStatistics.ps1 is not working in Exchange Server 2019
• 4538303 Exchange 2019 Setup Prerequisite Check fails for .NET 4.8 Framework in CU4 on Windows builds 1909 and 1903
• 4547705 Authentication loop between msft.sts.microsoft.com/adfs and OWA in Exchange Server 2019
• 4547706 Birthday isn’t correctly synced to iOS native mail app in Exchange Server 2019
• 4547708 Elevation of privileges possible when Active Directory permissions role is granted in Exchange Server 2019
• 4547709 InternetWebProxyBypassList is ignored by Mailbox Replication service in Exchange Server 2019
• 4547710 New-MailboxSearch with In-Place Hold enabled replaces all values in msExchUserHoldPolicies if adding a value in Exchange Server 2019
• 4547711 Public folder permissions aren’t applied from Outlook in Exchange Server 2019 hybrid environment
• 4547712 Outlook on the web (OWA) exposes junk operations even if disabled via OwaMailboxPolicy in Exchange Server 2019
• 4547713 IsOnlineMeeting is always false for Teams-only meetings in Exchange Server 2019
• 4547714 Can’t add remote shared mailbox using ECP into distribution group in Exchange Server 2019 hybrid environment
• 4547715 New created search folder retention policy is changed in Exchange Server 2019
• 4547719 MCDB status is “Offline” and SSDs are not formatted in Exchange Server 2019
• 4547720 Partial word searches not working for mailboxes in Outlook online mode in Exchange Server 2019
• 4547721 Exchange Sizing Calculator still supports mail.que database over 2 TB in Exchange Server 2019
• 4547722 Can’t go from Office 365 to Enterprise in Exchange Server 2019 Exchange admin center (EAC) if Chrome SameSite Cookie is enabled
• 4547723 Can’t sign in to Office 365 if configuring hybrid with Chrome SameSite Cookie enabled in Exchange Server 2019
• 4536987 Description of the security update for Microsoft Exchange Server 2019: February 11, 2020

Exchange 2016 CU16 fixes:

• 4547705 Authentication loop between msft.sts.microsoft.com/adfs and OWA in Exchange Server 2016
• 4547706 Birthday isn’t correctly synced to iOS native mail app in Exchange Server 2016
• 4547708 Elevation of privileges possible when Active Directory permissions role is granted in Exchange Server 2016
• 4547709 InternetWebProxyBypassList is ignored by Mailbox Replication service in Exchange Server 2016
• 4547710 New-MailboxSearch with In-Place Hold enabled replaces all values in msExchUserHoldPolicies if adding a value in Exchange Server 2016
• 4547711 Public folder permissions aren’t applied from Outlook in Exchange Server 2016 hybrid environment
• 4547712 Outlook on the web (OWA) exposes junk operations even if disabled via OwaMailboxPolicy in Exchange Server 2016
• 4547713 IsOnlineMeeting is always false for Teams-only meetings in Exchange Server 2016
• 4547714 Can’t add remote shared mailbox by using ECP into distribution group in Exchange Server 2016 hybrid environment
• 4547715 New created search folder retention policy is changed in Exchange Server 2016
• 4547722 Can’t go from Office 365 to Enterprise in Exchange Server 2016 Exchange admin center (EAC) if Chrome SameSite Cookie is enabled
• 4547723 Can’t sign in to Office 365 if configuring hybrid with Chrome SameSite Cookie enabled in Exchange Server 2016
• 4547716 Event ID 1325 and Test-ExchangeSearch crashes application pool with NullReferenceException in Exchange Server 2016
• 4536987 Description of the security update for Microsoft Exchange Server 2016: February 11, 2020

Notes:

• These Cumulative Updates do not contain schema changes compared to their previous Cumulative Update.
• When upgrading from an n-2 or earlier version of Exchange, or an early version of the .NET Framework, consult Upgrade Paths for CU’s & .NET.
• Don’t forget to put the Exchange server in maintenance mode prior to updating. Regardless, setup will put the server in server-wide offline mode post-analysis, before making actual changes.
• When using Exchange hybrid deployments or Exchange Online Archiving (EOA), you are required to delay installing at most one version (n-1).
• If you want to speed up the update process for systems without internet access, you can follow the procedure described here to disable publisher’s certificate revocation checking.
• Cumulative Updates can be installed directly; no need to install RTM prior to installing Cumulative Updates.
• Once installed, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles.
• The order of installation shouldn’t matter with the “every server is an island” concept, yet recommended is to upgrade internet-facing, non-internet-facing servers first, followed by Edge Transports.

Caution:

As for any update, I recommend to thoroughly test updates in a test environment prior to implementing them in production. When you lack such facilities, hold out a few days and monitor the comments on the original publication or forums for any issues.