Today, I helped a client migrate Exchange from 2010 to 2019. As you know, Exchange 2010 can’t migrate to 2019 directly. You need to migrate Exchange from 2010 to 2016 and then 2019.
When I tried to prepare the AD schema for installing Exchange 2016 CU23, and it happened the error message is below.
“One or more servers in the existing organization are running Exchange 2000 Server or Exchange Server 2003”.
The error is because they were not uninstalled Exchange 2000 or 2003 completed. Let’s fix it.