Recently I was at a customer site helping to get Exchange 2007 up in their lab environment. This customer in particular has a lot of projects going and just didn’t have time to implement all of them on their own (I’m seeing a lot more of this these days). The customer had gone through and done some Exchange 2007 work previously in the lab, but due to the incoming projects didn’t have time to finish it up. Due to this they ripped out what they had and left a somewhat semi-installed Exchange 2007 server in their Exchange 2003 org.
I know this scenario is fairly common. But the interesting thing I ran into was after I manually removed the remnants of the Exchange 2007 server they had left in the domain. I proceeded to install what would now be the first Exchange 2007 SP1 server, the CAS server and ran into an error right away….
The nominated Exchange server for offline address book ‘Default Offline Address’ has been deleted. Nominate a valid server and restart setup
This was a bit interesting and threw me off for a bit. After digging around a little I didn’t see any reference to what this meant. Upon investigation of the Exchange 2003 environment I found that the default offline address book in ESM was pointed to an entry with the format of “DC\GUID”, kind of odd…. so I simply re-pointed the address book to one of the Exchange servers that I knew was valid…. and voila :)
Hope this helps!!