If you are migrating from Exchange 2013 to Exchange 2019, you need to ensure the following before getting started:

Update Exchange 2013 with the latest Cumulative Update 23 (CU23) released in July 2021 or later.
Active Directory Servers must be hosted on Windows 2012 R2 Standard or Datacenter and higher with Windows Server 2012 R2 or higher Active Directory Forest functionality.
If you still host Windows 2008 R2 domain controllers, you need to make sure that these are decommissioned before the installation and migration of Exchange 2013 to Exchange 2019.
Exchange 2019 supports Outlook 2013 and higher.
Important Note: With Exchange 2019, you don’t have any Unified Messaging (UM). Thus, if you have Lync or Skype for Business Server, you will lose the ability to save voicemail messages in your mailboxes, and an alternative needs to be found, like CX-E or Azure Voicemail on Office 365.

Steps to Migrate Exchange Server 2013 to 2019
Deploy Exchange 2019
Install Windows Server 2019
Install Exchange 2019 Prerequisites
.Net 4.8 Framework
Visual C++ Redistributable Package for Visual Studio 2012 and 2013
Remote Tool, Administration Pack, and Windows Features

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