I'm in the middle of doing a on premise Exchange migration from 2003 to 2013 using 2010 as an intermididate server.
There are three DC's. One 2003 dc (sbs 2003) which was the primary dc before two other 2012r2 DC installed. I had no issues promoting those dcs and initial sysvol replication took place. The 2003 will be decommissioned.
What is happening is that group policy files are not consistent between the 2003 and 2012 DCs. The logs on the 2012 DC show Event ID 1791.
Replication of application directory partition DC=abc,DC=local from source 257088c5-3493-4b40-b79b-00f06d35d3ed (abc-sbs.abc.local) 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..
I have verified that the schema id's are the same, also for Exchange. Repadmin shows clean replication on all servers. I'm waiting to install Exchange 2013 and update the schema. I don't want to start this unless this problem is fixed. I'm at a loss to figure out what is going on. I'm not sure if this is related to the removal of Exchange 2003 from the 2003 server the previous night. I was also having another issue on my Exchange 2010 box where the Exchange services would not start. I had to add the Exchange server computer object to the Domain Admins group to fix it. Only mentioning this in case it's related, my feeling is some kind of permissions problem.