Exchange Server 2013 Upgrade to Exchange 2019 - AD Forest Function Level 2008R2

[Kashif_Saeed]

Dear Experts,

I am working on upgrade my existing Exchange Server 2013 environment to Exchange 2019 and during the verification of the pre-requisites which is forest function level to be 2012 R2 whereas in my case it is 2008R2. I have some legacy application and Database servers in my environment which runs on windows 2008R2 and if i upgrade the forest level to 2012 R2 the users will not be able to login. Please correct? The question is 

1- Any idea to upgrade the current environment while not upgrading the forest function level

2- Should I focus to upgrade to Exchange 2016, all pre-requisites successfully passed.

B 

[#2]

@Kashif_Saeed Changing the domain and forest level to a higher level than your lowest version of Windows Server doesn't make it impossible for users to logon to that lowest version of Windows server. The differences between the 2008 R2 and 2012 R2 level is described here https://docs.microsoft.com/en-us/windows-server/identity/ad-ds/active-directory-functional-levels . Please review those and see if there's anything there that could break your legacy application, could you contact the vendor of that application if possible?

2016 Exchange could be a solution, migration to Echange Online too ;) 

[#3]

@Harm_Veenstra, really appreciated your response, let me review the article and will get back to you if further assistance reqruied
Thanks,
Kashif Saeed

[#4 · Accepted solution]

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