After getting all three servers up to date when installing EBS 2008, you will likely find one update that refuses to install – .NET Framework 3.5 sp1.

The EBS Team blog has a nice Powershell script that *should* fix it, but there’s a bug in the script.
Microsoft .NET Framework 3.5 SP1 (KB951847) Fails to install on EBS Servers

At least, there is a bug when you try to run it after updating everything else (including the server to sp2).

at the line that looks like :

$goodvalue = $badvalue.$frameworkguid -replace ("D\?\\", "C\?\\")

The replacement string should be “C?\”. The search string requires the question mark and slash to be escaped, but the replacement string does not. It is supposed to replace “D?\” with “C?\”, but instead it replaces it with “C\?\\” — which exists even less than the original path!

I have created two helpful scripts.

First, if you have not already run the script from the EBS Blog, use this one instead:
dotnetfixup_fixed.ps1

If you have used the bugged version of the script use this script to fix it. You will now be able to install the .NET updates.
repair_bugged_fixup.ps1

These are run from an elevated powershell prompt, not a command prompt.

Good luck!