During an Active Directory domain controller upgrade from Windows 2003 to Windows 2012 R2 I observed replication issues on the Domain Controller which also owned the PDC emulator role.

A problem logging onto the domain controller is what initially triggered the investigation into potential issues. It is always a good idea to ensure replication and event logs are healthy before performing Active Directory changes and upgrades for situations like this.

Identifying the Error

repadmin /replsummary showed the following error:

Source DSA largest delta fails/total %% error<br /> DC-01 15m:05s 0 / 10 0<br /> DC-02 41m:15s 0 / 10 0<br /> DC-03 06d.05h:43m:01s 4 / 10 40 (2148074274) <strong>The target principal name is incorrect.</strong><br />

You can see DC-01 and DC-02 are fine but DC-03 has replication errors and shows the error message"The target principal name is incorrect.”

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Resetting the domain controllers computer account using the following steps resolved the replication issues.

Fixing the Issue

Step 1

Identify the DC which owns the PDC role:

netdom query fsmo

Step 2

On the domain controller, disable the Kerberos Key Distribution Center service (KDC).

Click Start, point to Programs, click Administrative Tools, and then click Services.<br /> Double-click KDC, set the startup type to Disabled, and then restart the computer.

(Restarting is required or else you will get an error on the next step)

Step 3

Login to the DC again and run the following command to reset the computer account.

netdom resetpwd /server:server_name /userd:domain_name\administrator /passwordd:administrator_password

(This can not be done in Active Directory Users and Computers for Domain Controllers.)

Step 4

Set the KDC service to “Automatic” again and restart the server again.

Step 5

Run the following commands to ensure there are no replication issues.

repadmin /syncall<br /> repadmin /replsummary

A clean replication summary looks like this:

Source DSA largest delta fails/total %% error<br /> DC-01 13m:10s 0 / 10 0<br /> DC-02 15m:05s 0 / 10 0<br /> DC-03 15m:05s 0 / 10 0<br />