Upgrade Active Directory form 2003 to 2019

[bcsnomi]

Hello All,

I am looking for some guidance to do Active directory upgrade from 2003 to 2019. Is it possible ? what are the best practices. 

[#2]

• The prerequisite before introducing the first 2016 domain controller: domain functional level needs to be 2003 or higher
• 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-SYS...

So it will be a two-step process as the 2003 domain controllers will need to be gone and FRS->DFSR migration will need to be done.

I'd use dcdiag / repadmin tools to verify health correcting all errors found before starting any operations. Then stand up the new 2016, 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 decommission / demote old one.

(please don't forget to mark helpful replies)