Tag Archives: schema

The replication operation failed because of a schema mismatch between the servers involved

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Last week I had deploy a new domain controller to the root domain in a forest (it happened to be an RODC for a unique use case, but that is irrelevant). The domain only partially replicated before failing and showing errors on the new DC.

The errors were:

Log Name:      Directory Service
 Source:        Microsoft-Windows-ActiveDirectory_DomainService
 Date:          1/4/2019 11:19:18 AM
 Event ID:      1791
 Task Category: Replication
 Level:         Error
 Keywords:      Classic
 User:          ANONYMOUS LOGON
 Computer:      rodc1.domain.com
 Description:
Replication of application directory partition DC=domain,DC=com from source 24c77a2c-6da0-41a1-95cf-e0542bca5b89 (dc1.domain.com) 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..
Log Name:      Directory Service
 Source:        Microsoft-Windows-ActiveDirectory_DomainService
 Date:          1/4/2019 11:19:31 AM
 Event ID:      1203
 Task Category: Replication
 Level:         Warning
 Keywords:      Classic
 User:          ANONYMOUS LOGON
 Computer:      rodc1.domain.com
 Description:
 The directory service could not replicate the following object from the source directory service at the following network address because of an Active Directory Domain Services schema mismatch. 
 Object:
 CN=Bob Smith,OU=Users,OU=All Users,DC=domain,DC=com 
 Network address:
 24c77a2c-6da0-41a1-95cf-e0542bca5b89._msdcs.domain.com

It was obvious that the object referenced in the second event was causing the issue, but this object was in use and I couldn’t just remove it. When looking for related errors on the source DC I found this:

Log Name:      Directory Service
 Source:        Microsoft-Windows-ActiveDirectory_DomainService
 Date:          1/4/2019 11:04:33 AM
 Event ID:      1450
 Task Category: Internal Processing
 Level:         Error
 Keywords:      Classic
 User:          ANONYMOUS LOGON
 Computer:      dc1.domain.com
 Description:
 The security descriptor propagation task could not calculate a new security descriptor for the following object. 
 Object:
 CN=Bob Smith,OU=Users,OU=All Users,DC=domain,DC=com 
 This operation will be tried again later. 
 User Action 
 If this condition continues, attempt to view the status of this object and manually change the security descriptor. 

Additional Data 
 Error value:
 1340 The inherited access control list (ACL) or access control entry (ACE) could not be built.

This was much more specific and showed there was an issue with the ACL of the object. I tried making one small change to the security ACL on the object to verify there was an issue and received an error. This ACL was either corrupt or too large. I decided to try repairing the ACL on the object by using ADSI Edit (adsiedit.msc) to remove everything from the ACL, add only ‘Domain Admins’ and ‘SYSTEM’ with Full Control, and then resetting it using DSACLS. I also had to do this for the ‘ExchangeActiveSyncDevices’ child object and the leaf objects under that since this user had Exchange ActiveSync devices. I verified the child and leaf objects were inheriting from the user object and proceeded to reset the ACL using the DSACLS:

dsacls "CN=Bob Smith,OU=Users,OU=All Users,DC=domain,DC=com" /S /T

After resetting the ACL replication to this domain controller completed with this event:

Log Name:      Directory Service
 Source:        Microsoft-Windows-ActiveDirectory_DomainService
 Date:          1/4/2019 11:49:51 AM
 Event ID:      1394
 Task Category: Service Control
 Level:         Information
 Keywords:      Classic
 User:          ANONYMOUS LOGON
 Computer:      rodc1.domain.com
 Description:
 All problems preventing updates to the Active Directory Domain Services database have been cleared. New updates to the Active Directory Domain Services database are succeeding. The Net Logon service has restarted.