Active Directory Roll Back Functional Level to 2003

How to Roll Back Functional Level after upgrade? We are upgrading our AD from Windows 2003 to Windows 2012 R2 AD. My question is just incase we run into issues with our upgrade and we need to roll back Domain Functional Level and Forest Functional Level what step we should take? I hear it is irreversible but any steps we should take just in case we need too.

Maybe systemstate backup? or shut down one DC down before raising the DFL/FFL? not sure if anyone did this successfully.
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Lee W, MVPTechnology and Business Process AdvisorCommented:
You cannot go back to 2003 functional levels.  In later versions, you can step back, I believe down to 2008 R2, provided you're not using any of the features that require newer levels.

You should also understand that functional levels essentially dictate the oldest DC you can have on the network.  Having a 2012R2 AD functional level means ALL your DCs must be 2012R2 or later.

Set your AD functional levels to the oldest DC on your network.  You should not be using 2003 anymore since it's no longer supported.  That means you should likely go AT LEAST to 2008.

As for restoring, again, you can't.  You should have backups of your network to begin with, but in the event you don't I'd backup your FSMO master DC.  Then, if there's a problem, turn off ALL other DCs and restore that one.  Then forcibly remove the others from the network and repromote them back with the FSMO holder restored.  Of course it could be more complicated depending on how many DCs you have.  2?  50?  What -- you didn't mention.

That said, raising functionality is as safe as you can get - I've never heard of or experienced an issue with it... except for people who don't understand what it does and they have raised it above (or tried to) the oldest DC on the network.  You could always be the first, but I'd put it at a 99.999% safe thing to do.

Finally, if you don't have the understanding and/or knowledge to do this - including confidence, you really should hire a pro.
stghelpdeskAuthor Commented:
We have 4 DC's in Root domain and 10 DC's on Child Domain (all the users accounts, Computers accounts, Servers, DNS, DHCP are on)
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Kamal KhaleefaInformation Security SpecialistCommented:
Why you want to roll back
Did you get errors with sso ,spenago,oracle component ?
Luis MouraCommented:
Set the Ad funcional level with the old DC.
After upgrade,all old DC.
You can upgrade the level.
stghelpdeskAuthor Commented:
So here is plan.. on 11/7 we are upgrading all DC from 2003 to 2012 R2 (all new hardware and upgrading OS to 2012) Demoting all 2003 OS DC. but stilling running  DFL/FFL in 2003.

On 11/21 we will be raising  DFL/FFL from AD 2003 to AD 2012 on all DC's. As off right now I am looking for blackout plan for this.. I am thinking two options  they are...

option 1.      Perform a Full System State Backup using ‘Windows Server Backup (Local)’ on  ALL Domain Controllers.

option 2. Create new  2012 R2 Domain Controllers prior to functional level upgrade then shut them off prior to raise the DFL/FFL.

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stghelpdeskAuthor Commented:
Below plan worked great
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Windows Server 2003

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