Recently working on one of the MOSS farms, I came across an interesting scenario during the SP1 upgrade process. One of the web front end servers had MOSS 2007 RTM and WSS 3.0 Infrastructure Update (June 2008 Update) installed. Our client wanted to upgrade the server to the MOSS 2007 SP1 and WSS 3.0 SP1, which was released in the December 2007 (earliar than Infrastructure Update).
At first sight, this seems straightforward. Since server has MOSS 2007 RTM installed, it’s no brainer that you can install the SP1 binaries on the server. But, central admin web site (servers in the farm page) and database schema versions shows that server has been upgraded to the WSS Infrastructure Update due to WSS update installed on the server which was released later date than SP1.
So, the question – Can you install the SP1 on the server upgraded with later date release updates or patches?
As it turned out, answer was YES.
Here are more details from the Microsoft – Microsoft allows the installation of update, hot fix, or patches on the MOSS RTM servers without requiring the installation of the latest service pack release. It means, you can install the Infrastructure Update (June 2008 release) on the MOSS RTM Server without installing the Service Pack 1 (December 20007 release).
In short, we were able to install WSS SP1 and MOSS SP1 on the server with WSS Infrastructure Update successfully. Interestingly, After the SP1 upgrade, MOSS was upgraded to MOSS SP1 but WSS wasn’t rolled back rightly to the SP1, leaving it at the Infrastructure Update level.