Error getting the list of sites from the target environment: An invalid dn syntax has been specified

Trying to add another (second) Domain Controller to an existing Domain. In the second step of “Active Directory Domain Services Configuration Wizard” getting the following error:

Error getting the list of sites from the target environment: An
invalid dn syntax has been specified.

Due to the above error, the “Site name” dropdown is empty. Here is the screenshot.

PS: Both the main Domain Controller (current one) and the one that I’m trying to add run on Windows Server 2012. The operation level of AC and Domain Control is also Windows Server 2012.

What is wrong?