Unable to promote Win2012r2 server to a DC and add to existing domain

I have a 2008 domain and I'm trying to add another DC to it, which is running Windows Server 2012r2
When I try to promote to a DC, it fails on prerequisite check with the following error:

Verification of prerequisites for Active Directory preparation failed. Unable to verify whether schema master has completed a replication cycle after last reboot.
Exception: Unavailable Critical Extension. Server extended error: 8366. Server extended message: 000020AE: SvcErr: DSID-03210384, problem 5010 (UNAVAIL_EXTENSION), data 8610
Adprep failed to verify whether schema master has completed a replication cycle after last reboot.
The schema is not upgraded.
[User Action]
Check the log file ADPrep.log in the C:\Windows\debug\adprep\logs\20151010161101-test directory for possible cause of failure.

I ran adprep manually on my 2008 DC and it said: Domain-wide information has already been updated.
Adprep did not attempt to rerun this operation.
Selma DNetwork AdminAsked:
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David Paris VicenteSystems and Comunications  Administrator Commented:
Hi Selmaa,

Can you give us more details about your domain.
How many domain controllers do you have with windows 2008?
Windows 2008 version?
Level of your forest in 2008?

Thank you.

Selma DNetwork AdminAuthor Commented:
Hi David,

I have 2 DCs  and they're both Win 2008 R2.  Functional level is 2008
David Paris VicenteSystems and Comunications  Administrator Commented:
Hi again just one thing I forgot to mention.

Can you run the repadmin and showrepl commands and past them here?

Or you can use this tool from Microsoft to discover replication problems and where they are.


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David Paris VicenteSystems and Comunications  Administrator Commented:
Thanks for your prompt response.

Can you check with the tools mentioned on my last post for replication problems?
Are your DNS working properly?
Both servers are turned on?
You can't promote a server that already is a DC to another domain. First make sure it is not a DC and not a member of any domain. Then add the server to the domain, and after that promote it to a DC.
Selma DNetwork AdminAuthor Commented:
I ran the tool and it's come back with some errors.  But that's probably because the two DCs are currently separated by firewall, since one of them is at the Disaster Recovery site.
I need to change the firewall settings and I'll run it again, but it might be in 2-3 days when I have my next change window.
I will let you know.

I am not sure I've explained my problem properly, but the server I'm trying to promote to a DC is not a DC yet :)
David Paris VicenteSystems and Comunications  Administrator Commented:
Hi Selmaa,

Thank you for your feedback.

Probably that is the problem. Both 2008 DC need to replicate properly and the replication needs to be in good stand.

After the networking issue is solved, try to force the replication and then run again the tool.

Let us know.



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Selma DNetwork AdminAuthor Commented:
As it turns out, I couldn't fix the replication issues because the time last replication happened exceeded the tombstone lifetime.
So I decided to demote the DC that was dormant (DR site) and proceed with the new DC promotion (Win server 2012).  
Finally, it was promoted successfully.

Thanks for your help!!
David Paris VicenteSystems and Comunications  Administrator Commented:
Hi Selma,

Thank you for your feedback.

That was my concern but I had hopes that we had time to force the replication. and get the DC outside of tombstone flag.

What counts now is that the problem is solved.


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Windows Server 2012

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