Exchange server uprgrade

Question

Hello Team, We have hybrid setup whereas we have exchange 2016 and the license shows Coexistance edition, can anyone clarify we do we need to first migrate to 2019 then inplace upgrade to exchange SE or can we directly do legacy upgrade to exchange SE, Do we need to purchase the separate license for this or will HCW assign the co-existence license and could you please help what will be the steps need to perform for migrations we have two VM for exchange server 2016 and have DAG configured and these two VMS are in ALB, when we check there is frontend is baracuda and backend pool these two VM's is located.
When we need to run the HCW, for introducing the new servers

Answer 1

Hi @Achari, Sumit Kumar 

Thank you for posting your question in the Microsoft Q&A forum. 

Based on Microsoft documentation, you cannot perform an in-place upgrade directly from Exchange 2016 to Exchange SE. If you want to re-use existing servers, you must first upgrade your Exchange 2016 environment to Exchange 2019 (install new 2019 servers, move mailboxes/resources, and decommission Exchange 2016). Once on Exchange 2019 CU14 or CU15, you can then perform an in-place upgrade to Exchange SE. 

Alternatively, you can perform a legacy upgrade directly from Exchange 2016 to Exchange SE. This involves deploying new SE servers into your environment, migrating mailboxes/resources from Exchange 2016, and then removing the old servers. 
You can read more at Upgrading to Exchange Server Subscription Edition (SE) | Microsoft Learn 
The Exchange Hybrid Configuration Wizard (HCW) grants you a free Hybrid/Coexistence license for Exchange only when you run HCW and integrate with Exchange Online. 

Please note that the Hybrid license is for the purposes of recipient management only. If you host mailboxes, need an Edge Transport or SMTP relay server on-premises, you still need an Exchange Server license.   
For Exchange Server SE, in addition to purchasing the required Server licenses and CALs, customers must also maintain an active subscription. This means purchasing either: 

-Cloud subscription licenses for all users and devices that access Exchange Server SE (for example, Microsoft 365 E3 or E5 licenses); or 

-Exchange Server SE Server licenses and CALs with Software Assurance.  If your end goal is to run just a hybrid server (no mailboxes), you can still use the free Hybrid Coexistence license that HCW assigns. 

References: 
Microsoft Exchange Server licensing and FAQ– email for business 
Upgrading your organization from current versions to Exchange Server SE | Microsoft Community Hub 
-When migrating, ensure your Database Availability Group (DAG) is healthy and that both Exchange 2016 and 2019 servers are properly configured in your Application Load Balancer (ALB) and Barracuda frontend. You will need to:  

• If you’re following the 2016 → 2019 → SE path, you can add Exchange 2019 servers to the DAG alongside 2016. If you deploy SE servers directly, they cannot join a 2016 DAG. You must create new databases on SE and migrate mailboxes there. 
• Move mailboxes from Exchange 2016 to 2019 or move mailboxes from Exchange 2016 directly to Exchange SE, if you are doing the legacy upgrade path. 
• Update ALB and Barracuda configurations to point to the new servers as you transition. 
• Remove Exchange 2016 servers from the DAG and decommission them after migration 

-You can run HCW from any supported Exchange server. Run the HCW after introducing the new Exchange 2019 servers but before moving mailboxes to ensure hybrid mail flow and features are properly configured. You may need to rerun HCW after the migration to update connectors and settings. 

I hope this information is helpful. 

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