Azure AD sync fails delta import with status stopped-connectivity

Question

Just migrated our ADsync to new 2016 server following this guide: https://blog.expta.com/2021/07/how-to-migrate-aad-connect-to-new-server.html

Now with every new synccycle on the new server Im getting this Event ID 6050:

- <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
- <System>
  <Provider Name="ADSync" /> 
  <EventID Qualifiers="49152">6050</EventID> 
  <Level>2</Level> 
  <Task>1</Task> 
  <Keywords>0x80000000000000</Keywords> 
  <TimeCreated SystemTime="2023-01-24T16:27:34.519869300Z" /> 
  <EventRecordID>8651</EventRecordID> 
  <Channel>Application</Channel> 
  <Computer>AzureAdSync.xxxxxxxxxxx.xx</Computer> 
  <Security /> 
  </System>
- <EventData>
  <Data>mydomain.xxx</Data> 
  <Data>Delta Import</Data> 
  <Data>0</Data> 
  <Data>0</Data> 
  <Data>0</Data> 
  <Data>0</Data> 
  <Data>0</Data> 
  </EventData>
  </Event>

Synchronization Service Manager shows that is is the Delta Import for our-domain that fails with the error 'The replication operation encountered a database error', error code 8451. The delta import for our-domain.onmicrosoft.com ends with succes, as do all the other synchronization tasks:

Any ideas to what the cause of this might be? I'm a little stumped :(

Regards

/Ulrik

Answer 1

Do you have multiple DCs? So you can move the PDC role to another server.

For that error from the doc above:

Answer 2

Are the Domain controllers healthy?

[https://learn.microsoft.com/en-us/troubleshoot/windows-server/identity/active-directory-replication-error-8451https://learn.microsoft.com/en-us/troubleshoot/windows-server/identity/active-directory-replication-error-8451

Answer 3

Hi @Ulrik Sieverts

Check if adconnect server still able to contact the DC mentioned in the adconnect sync console on LDAP port 389:

Test-NetConnection -Port 389 -ComputerName DC.domainName.lan

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Answer 4

Seems my comments are dissapearing? I'll try again:

Thank you for the answers!

LDAP connection from the adsyncserver and my pdc is working:

ComputerName     : DC.mydomain.xxx 
RemoteAddress    : 192.168.255.18 
RemotePort       : 389 
InterfaceAlias   : Ethernet 
SourceAddress    : 192.168.8.227 
TcpTestSucceeded : True

AD seems healthy. Repadmin and dcdiag shows no errors.

I have however noticed that I get this error on my PDC with every synchronization attempt:

- <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
- <System>
  <Provider Name="Microsoft-Windows-ActiveDirectory_DomainService" Guid="{0e8478c5-3605-4e8c-8497-1e730c959516}" EventSourceName="NTDS Database" /> 
  <EventID Qualifiers="49152">1168</EventID> 
  <Version>0</Version> 
  <Level>2</Level> 
  <Task>9</Task> 
  <Opcode>0</Opcode> 
  <Keywords>0x8080000000000000</Keywords> 
  <TimeCreated SystemTime="2023-01-25T10:08:57.839237900Z" /> 
  <EventRecordID>30786</EventRecordID> 
  <Correlation /> 
  <Execution ProcessID="636" ThreadID="3504" /> 
  <Channel>Directory Service</Channel> 
  <Computer>pdc.mydomain.xxx</Computer> 
  <Security UserID="S-1-5-21-3135561391-2215252232-3658666570-29115" /> 
  </System>
- <EventData>
  <Data>-1601</Data> 
  <Data>fffff9bf</Data> 
  <Data>2070ab5</Data> 
  <Binary>0A07000000000000A8340000A7000000</Binary> 
  </EventData>
  </Event>

So it seems there is something wrong/corrupt in my NTDS database :-(

Answer 5

Hi @Ulrik Sieverts ,

Did you try to specify another DC from connector settings ?

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