Error in replication of newly installed ADC in Windows server 2016- schema version mismatch

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manuchamp asked · Mar 01 at 11:13 AM

Error in replication of newly installed ADC in Windows server 2016- schema version mismatch

Hi,
I have an AD environment with 8 ADC running 2008 R2, 1 ADC running 2012 R2. The root DC is running 2008 R2. We are functional level 2003.
We need to upgrade the base OS in phase manner and eventually get rid of all the older version.

We have installed a new ADC on OS 2016 Std, and facing issue in replication. Below is the error:

Replication of application directory partition DC=xxx,DC=com from source <xxxxxxx>) has been aborted. Replication requires consistent schema but last attempt to synchronize the schema had failed. It is crucial that schema replication functions properly. See previous errors for more diagnostics. If this issue persists, please contact Microsoft Product Support Services for assistance. Error 8418: The replication operation failed because of a schema mismatch between the servers involved..

Also event ids 1203 are observed specifying the schema mismatch. I have verified the schema version is 87, which is the default version of AD on windows server 2016. The root DC shows the schema update successful event log as well.

Need help to resolve the issue.

Also what if i decided to demote this failed ADC installation, does it have any impact in my running environment.

Pls help.

windows-server-2016

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DaisyZhou-MSFT · Mar 05 at 09:25 AM

Hello @manuchamp,
Would you please tell me how things are going on your side. If you have any questions or concerns about the information I provided, please don't hesitate to let us know.
Thanks for your time and have a nice day!

Best Regards,
Daisy Zhou

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DaisyZhou-MSFT · Mar 09 at 03:37 AM

Hello @manuchamp,
How are things going on your end? Please keep me posted on this issue.
If you have any further questions or concerns about this question, please let us know.
I appreciate your time and efforts.

Best Regards,
Daisy Zhou

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manuchamp DaisyZhou-MSFT · Mar 09 at 04:06 PM

Hi
I am still validating the things and will surely reply on this week. Was on the exchange critical patch updating on the production environment so thing got delayed. Thank for patience.

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DaisyZhou-MSFT · Mar 15 at 06:07 AM

Hello @manuchamp,
I just want to confirm the current situations.
Please feel free to let us know if you need further assistance.

Best Regards,
Daisy Zhou

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Answer 1 · 2021-03-01T13:53:52.443Z

DSPatrick answered · Mar 01 at 01:53 PM

I'd work through this one.
https://docs.microsoft.com/en-us/troubleshoot/windows-server/identity/replication-error-8418

--please don't forget to Accept as answer if the reply is helpful--

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manuchamp · Mar 01 at 02:36 PM

Thanks I will surely work on this and update.
One thing need advice on , can I just demote the newly installed ADC. Will it downgrade the schema version? Will there be any impact.

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DSPatrick manuchamp · Mar 01 at 02:40 PM

Yes, you can move roles of and demote the new domain controller. No it will not downgrade schema. No, should not be any impact.

--please don't forget to Accept as answer if the reply is helpful--

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Answer 2 · 2021-03-02T05:49:37.967Z

DaisyZhou-MSFT answered · Mar 02 at 05:49 AM

Hello @manuchamp,

Thank you for posting here.

Based on the description "I have verified the schema version is 87", do you mean the schema version on all DCs is 87?

From the error message, maybe there is AD replication issue between the new 2016 DC with the existing DC or between the existing DCs.

Have you check the AD replication status before you added the new 2016 DC? If no, we can demote the new 2016 DC and after that check AD replication status by running the following commands.

repadmin /showrepl >c:\repsum1.txt

repadmin /replsum >c:\repsum2.txt

**repadmin /showrepl /csv >c:\repsum.csv*

If there is no any error message in the result, it means AD replication works fine.

Then we can add new 2016 DC again.

Hope the information above is helpful.

Should you have any question or concern, please feel free to let us know.

Best Regards,
Daisy Zhou

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manuchamp · Mar 09 at 04:06 PM

Thanks Daisy. I will check this and reply

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DaisyZhou-MSFT manuchamp · Mar 10 at 06:30 AM

Hello @manuchamp,

Thank you for your update.

If anything is unclear, please feel free to let us know.

Have a nice day!

Best Regards,
Daisy Zhou

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