Migrating from SBS2003 Exchange SP2 to Server 2012STD /Exchange STD 2010SP3. Exchange installation failed before I realized I needed SP3 to install on Server 2012. Installation completed with no errors after SP3, however I am now unable to create a Mailbox store on the Exchange 2012 server in order to move mailboxes from SBS2003 Exchange. Unable to remove EX2010 to start again. EX2003 connections already established via Exchange console commands.
12 User system, all roles are on the same server.
Just a mail migration, no public folders or distribution lists.