Error Installing KB976462 during SharePoint Pre-Requisites Installer

I was running the SharePoint Pre-Requisites installer this week. Upon competition it failed to install KB976462 and then skipped the rest of the installers. It turns out a second running of the installer then successfully installed the rest of the pre-requisites. I could have just continued on my merry way, but having a weird issue like this hanging out there can usually lead to some very strange issues further along in the install process so I dug in to figure out what was wrong.

The first step was to figure out what the KB was and this lead me to the Microsoft kb article for it:
http://support.microsoft.com/kb/976462. It turns out this is a patch to the .NET framework 3.5 SP1, this seems like a crucial thing to have installed properly. Next I logged into one of the other servers provided to me and checked to see what versions of .NET was installed. In order to determine the .NET versions I navigated to the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\ upon viewing the versions installed in this key I noticed that only version 2 or .NET was installed.

On this other machine I then used the proper method to activate .NET v3.5.1 by adding the windows feature from the server management console. After the feature was activated windows update was run to make sure that all of the current patches for .NET were downloaded and installed. After the feature was activated and windows update was run the pre-requisite installer was executed and it ran without any errors.

To be on the safe side I had the first server rebuilt because installing SharePoint on a server with an improperly installed .NET v3.5.1 did not seem like a good path to go down.

The username is invalid. The account must be a valid domain account

Today while configuring a farm I stumbled across a weird error I have never seen before. Upon entering the credentials for our farm account and error message popped up stating: "The username is invalid. The account must be a valid domain account."

As part of our deployment we wanted to make our account names very descriptive of what they were used for. This policy led us to use a very descriptive and lengthy account name that was similar to SP2010_ServerFarmAccount. This seemed like a great idea at the time because it is very obvious what this account was used for. But as it turns out lengthy user names might be a bad idea in a Windows environment.

Those people out there who are Active Directory administrators might already know what is coming up as the root of this problem. It turns out that Active Directory will let you make very lengthy user names; unfortunately there is a second field that is kept around for legacy purposes that truncates the user name to 20 characters. So using domain\SP2010_ServerFarmAccount was not the proper thing to do because the account gets truncated for authentication purposes to domain\SP2010_ServerFarmAcc.

The solution to this problem is pretty easy. Login using either the legacy form domain\SP2010_ServerFarmAcc or if you prefer to use the whole user name you can use the more modern format SP2010_ServerFarmAccount@domain.fqdn.