While I was supporting a client I came across an issue where one of the updates failed on the Management server in an EBS installation. Maybe failed is the wrong term to use as the update reported that it would install successfully, but the next day or so (or if you manually kick of the detection logic) that update would reappear. Strange.
Looks like this is a known issue. The update in question is the SQL Server 2005 with Advanced Services SP3 (KB955706). Turns out that on my specific installation, it had upgraded the SQL Database instance but the Reporting Services instance hadn't been updated to SP3. This is why the update is re-offered. When I attempted to install the update manually, it would stop me indicating that none of the components were able to be upgraded.
As I said before, it was a known issue. The fine folks on the EBS Team Blog have an article about it here, and my problem was resolved successfully. But why does this happen?
I was curious.
Turns out, when you launch the update, it runs the Best Practices Analyzer and notices that the ASP.NET version enabled on IIS does not allow 32-bit application pools. This is a problem as the service pack needs this enabled to upgrade the reporting services instance. It is important to remember to change this back though, as applications will use 32-bit ASP.NET and not the native 64-bit bits. Since the EBS Admin Console likes 64-bit if you don't change this setting back your console will crash.