In my case I was trying to update SQL Server Management Studio (SSMS) from 2005 to 2008. Yea, I know it is 2012 but the 2005 stuff was working. As a general rule I don’t mess with stuff that is working but 2008 SSMS is a simple way to get 2008 SMO for PowerShell. The 2008 SSMS installation complained about the existing 2005 version and asked me to uninstall the 2005 version before proceeding. After I uninstalled the 2005 version I resumed the 2008 installation and it generated this error message.
SQL Server Setup has encountered the following error:
Unable to generate a temporary class (result=1).
error CS0006: Metadata file ‘C:\WINDOWS\assembly\GAC_MSIL\MSClusterLib\220.127.116.11__89845dcd8080cc91\MSClusterLib.dll’ could not be found
Error code 0x84B10001.
Although some folks recommended repairing the SQL installation, my fix was simple. I restarted the 2008 installation and it re-installed the missing items.