Server 2012 in place upgrade to 2019 on single DC enviroment

Question

Are there any special steps I need to take before performing an in-place upgrade from a 2012 R2 domain controller to 2019? This is a single domain controller environment. Is this even possible?

Answer 1

Its risky and never recommended to do an in-place upgrade, especially a domain controller. Better option is to stand up a temporary domain controller and move roles over to it (even on desktop hardware) will do.

The two prerequisites to introducing the first 2019 domain controller are that domain functional level needs to be 2008 or higher and older sysvol FRS replication needs to have been migrated to DFSR
https://techcommunity.microsoft.com/t5/Storage-at-Microsoft/Streamlined-Migration-of-FRS-to-DFSR-SYSVOL/ba-p/425405

I'd use dcdiag / repadmin tools to verify health correcting all errors found before starting any operations. Then stand up the new 2019, patch it fully, license it, join existing domain, add active directory domain services, promote it also making it a GC (recommended), transfer FSMO roles over (optional), transfer pdc emulator role (optional), use dcdiag / repadmin tools to again verify health, when all is good you can move on to next one.

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